Well it won't help with a rotary cell phone but you can do all the megasquirt does with JY GM parts. Still need a laptop, TunerPro tuning software is $30. and all definitions are free and will do 100's of cars, cable is about $50. Burner $85 and a newer EEPROM and adapter $40. from Moates.
when done you still have equiptment to do other cars with another adapter and chip.
GM EFI systems are very well supported!
JY ECM is cheap and several will run stock $58 mask from GM that came on turbo cars with 2 bar MAP sensor for boost. Or others that did not have boost can still run an enhanced version called/at Code59.org