That's awesome. Honestly, 10kpA increments from 50-100 is fine. I use similar scales a lot in the Megasquirt world-unless you're running a cam that really doesn't make much vacuum then all your fine tuning is usually under 65kpA or so. Above that, 10 or even 15kpa per increment is perfectly usable, as long as the tables are being interpolated.

I sat down and took a look at re-learning what I'd need to know the other day-would have been january before I felt ready to tackle something like this!

The spark table sounds...odd. But, there really isn't much need to add or remove timing advance past 3000ish RPM in most engines, so I can see why it was done that way.

Whatever you come up with-I am 100% certain it will be perfectly usable. Making this PCM boost-capable opens up a huge window for the Camaro/Firebird folks who want to turbo their car, but don't want to do a complete OBD1 wiring swap. (also Beretta, as the manual trans PCM I have is from a 3100 powered beretta!)