most old 160 baud slow ass old tbi ECMs (which are probably older than the original nintendo entertainment system and have about the same processing power) have a newer 8192 baud cousin that is quite easy to re-pin for and better to tune. that'd be much easier than a megasquirt which is a total do-over.

you can really use most any TBI with most any TBI ECM if you are handy enough

edit: but to answer your original question, yeah, megasquirt is just great. really nice product. tuned 2 of them now, difficulty medium but rewards are great