here an example of the changes zip plugin for me now targets azw3, input was kepub in calibre.
Convert book 1 of 1 (title here)) edited the ebook name out of this example
Resolved conversion options
calibre version: 2.69.0
{'asciiize': False,
'author_sort': None,
'authors': None,
'base_font_size': 0.0,
'book_producer': None,
'change_justification': u'original',
'chapter': u"//*[((name()='h1' or name()='h2') and re:test(., '\\s*((chapter|book|section|part)\\s+)|((prolog|pr ologue|epilogue)(\\s+|$))', 'i')) or @class = 'chapter']",
'chapter_mark': u'pagebreak',
'comments': None,
'cover': u'C:\\Users\\ROBERT~1\\AppData\\Local\\Temp\\calib re_gtraau\\jnngvp.jpeg',
'debug_pipeline': None,
'dehyphenate': True,
'delete_blank_paragraphs': True,
'disable_font_rescaling': False,
'dont_split_on_page_breaks': False,
'duplicate_links_in_toc': False,
'embed_all_fonts': False,
'embed_font_family': None,
'enable_heuristics': False,
'epub_flatten': False,
'epub_inline_toc': False,
'epub_toc_at_end': False,
'expand_css': False,
'extra_css': None,
'extract_to': None,
'filter_css': u'',
'fix_indents': True,
'flow_size': 260,
'font_size_mapping': None,
'format_scene_breaks': True,
'html_unwrap_factor': 0.4,
'input_encoding': None,
'input_profile': <calibre.customize.profiles.InputProfile object at 0x0000000005D33320>,
'insert_blank_line': False,
'insert_blank_line_size': 0.5,
'insert_metadata': False,
'isbn': None,
'italicize_common_cases': True,
'keep_ligatures': False,
'language': None,
'level1_toc': None,
'level2_toc': None,
'level3_toc': None,
'line_height': 0.0,
'linearize_tables': False,
'margin_bottom': 5.0,
'margin_left': 5.0,
'margin_right': 5.0,
'margin_top': 5.0,
'markup_chapter_headings': True,
'max_toc_links': 50,
'minimum_line_height': 120.0,
'no_chapters_in_toc': False,
'no_default_epub_cover': False,
'no_inline_navbars': False,
'no_svg_cover': False,
'output_profile': <calibre.customize.profiles.KoboReaderOutput object at 0x0000000005D33A58>,
'page_breaks_before': u"//*[name()='h1' or name()='h2']",
'prefer_metadata_cover': False,
'preserve_cover_aspect_ratio': False,
'pretty_print': True,
'pubdate': None,
'publisher': None,
'rating': None,
'read_metadata_from_opf': u'C:\\Users\\ROBERT~1\\AppData\\Local\\Temp\\calib re_gtraau\\jeszon.opf',
'remove_fake_margins': False,
'remove_first_image': True,
'remove_paragraph_spacing': False,
'remove_paragraph_spacing_indent_size': 1.5,
'renumber_headings': True,
'replace_scene_breaks': u'',
'search_replace': '[]',
'series': None,
'series_index': None,
'smarten_punctuation': False,
'sr1_replace': None,
'sr1_search': None,
'sr2_replace': None,
'sr2_search': None,
'sr3_replace': None,
'sr3_search': None,
'start_reading_at': None,
'strip_kobo_spans': False,
'subset_embedded_fonts': False,
'tags': None,
'timestamp': None,
'title': None,
'title_sort': None,
'toc_filter': None,
'toc_threshold': 6,
'toc_title': None,
'transform_css_rules': '[]',
'unsmarten_punctuation': False,
'unwrap_lines': True,
'use_auto_toc': False,
'verbose': 2}
InputFormatPlugin: KePub Input running
on C:\Users\ROBERT~1\AppData\Local\Temp\calibre_gtraa u\oefrjs.kepub
KEPUBInput::convert - start
Found HTML cover titlepage.xhtml
Parsing all content...
Parsing text/part0001.html ...
Parsing kte-css/stylehacks.css ...
Parsing text/part0000.html ...
Parsing titlepage.xhtml ...
Parsing stylesheet.css ...
Parsing kte-css/hyphenation.css ...
Parsing page_styles.css ...
Referenced file u'text/XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX' not found
Reading TOC from NCX...
KEPUBInput:
ostprocess_book - start
KEPUBInput:
ostprocess_book - not stripping kobo spans
Merging user specified metadata...
Detecting structure...
Flattening CSS and remapping font sizes...
Source base font size is 12.00000pt
Cleaning up manifest...
Trimming unused files from manifest...
Trimming u'plugininfo.kte' from manifest
Trimming u'titlepage.xhtml' from manifest
Creating azw8 Output...
Software versions: azw8 Output 1.3.0, calibre 2.69 [64bit], Windows-8-6.2.9200
azw8 Output plugin help is available at
https://www.mobileread.com/forums/sho...d.php?t=272407
Rescaling image from 925x1388 to 457x686 cover.jpeg
Splitting markup on page breaks and flow limits, if any...
Looking for large trees in text/part0001.html...
Found large tree #0
Splitting...
Split point: {http://www.w3.org/1999/xhtml}div /*/*[2]/*
Split tree too small
Splitting...
Split point: {http://www.w3.org/1999/xhtml}p /*/*[2]/*/*/*[10]/*/*[11]
Committed sub-tree #1 (133 KB)
Committed sub-tree #2 (144 KB)
Split into 2 parts
Looking for large trees in text/part0000.html...
Found large tree #0
Splitting...
Split point: {http://www.w3.org/1999/xhtml}div /*/*[2]/*
Split tree too small
Splitting...
Split point: {http://www.w3.org/1999/xhtml}p /*/*[2]/*/*/*[11]/*/*[38]
Committed sub-tree #1 (144 KB)
Committed sub-tree #2 (137 KB)
Split into 2 parts
This EPUB file has no Table of Contents. Creating a default TOC
Successfully converted input format to EPUB
Converting "C:\Users\ROBERT~1\AppData\Local\Temp\calibre_gtra au\1o88lz.epub" to KDF/KPF
Preparing EPUB for conversion
Launching Kindle Previewer EpubToKFXConverter (version 3.5.0)
Successfully converted EPUB to KPF/KDF
Processing container: C:/Users/ROBERT~1/AppData/Local/Temp/calibre_gtraau/yqr0ie.kpf:resources/book.kdf
Successfully converted KPF/KDF to azw8
AZW8 output written to C:\Users\ROBERT~1\AppData\Local\Temp\calibre_gtraa u\wevkvs.azw8