No, what I want is to use the original class pretty much as-is, but layer on some additional perks and options that make the class more appealing and fun to play. I know a lot of people will argue that it's fun to play the original Thief without any house rules, and that's fine if it's your jam. Personally I just don't want to play a fantasy character who has a 10% chance to do the one thing they are "good" at doing. And I am really not sure why the original designers went with such a dreadful way of thinking. Maybe they assumed very low level play would be only a tiny portion and most people would play at over 10th level? I dunno. In my experience most people play between 1 and 9.
Anyway... I've mentioned a shitload of Thief house rules, because it's fairly easy to house rule this game into the stone age. But for Doomslakers I really want to keep that class unchanged as much as possible.
So my current thinking is that the setting itself will provide the layers of perks and house rules. It is a setting book, after all, not a generic manual. So when you roll up a Doomslakers Thief you'll choose a Guild and there are only a small number of Guilds in the world. Each has its own secrets. So the Guild you pick will modify your base skill ratings and grant you certain additional perks. THIS SHIT IS FUN.
Why do I want to avoid changing the original classes? Particularly the class tables...
Because Doomslakers B/X is a love letter, if I'm being completely saccharine. It is meant to be a 64 page saddle stitched book you can use in direct conjunction with the original game books (or OSE, Lab Lord, etc... you know the drill). It is a resource for that game not an altogether new game. It stems from the B/X 64 Challenge from the G+ days where I suggested that people should try to create a B/X supplement in 64 pages within 6 months (or something like that).