Your best bet with IMB PC is just porting
PCem (or
86Box). But those have no savestates, so they'd have to be waterboxed. But waterbox build environment has been recently posted and tested, so it's at least now possible to use it again. Cool thing about PCem is that it can run DOS, Windows, Linux, Adobe Flashplayer, JRE8 applications, and whatnot. A pure monster.
For Amiga there's a full-blown thing called
FS-UAE that's being rapidly developed and kept up-to-date with WinUAE, but has an advantage of being cross platform and hosted by a more friendly dev. And it has savestates. It'd be an interesting task to port given the infrastructure, but probably still easier than PCem.
Developing emulation for these from scratch looks like a waste of time to me if instead existing emulators could be improved and reused.