Not including any fast RAM is also going to be a big performance
penalty. Either way, this is a massive project.
Something I thought about a few years ago was desoldering the
A600's 68000, adding a socket, and dropping in a pin-compatible 68010.
Negligible speed improvement, but it would have a VBR which is helpful
for WHDLoad.
I'm hoping Jens Schoenfeld brings his A600 accelerator into production
soon.