I know almost nothing about HW. But when I saw the design I thought it was a replacement for the old PPC-Blizzard-PPC-like accelerators. 100% compatible (including Binary compatibility for sure) with new features added.
The problems with making a CSPPC clone are many. It was a super complex card with no documentation and the people who know exactly how it worked aren't telling. Also CPU's have changed dramatically since then, the buses aren't even remotely as compatible with 68k as they were then those cards were produced. External local bus masters as we know them are ancient history so it would be a major redesign with lessened compatibility.
Compound that with the fact that getting AOS or MorphOS ported to even a platform closely related to existing ones is pretty much out of the question actually makes alternative CPU's like this an option.
My suggestion would be to run it like a hyper fast 680x0 and forget native code.
The OS is already available.
The apps are available.
Apps designed for it would still run on other Amigas and emulators.
If faster, cheaper SOCs become available you can jump ship without breaking the OS and apps.
A vast number of Amiga users never had a PPC anyway, thus have no investment in compatibility. They all have an investment in 68k.
A 500Mhz+ 68040 would be nothing to scoff at. I'd certainly use one.