I will give you my 2 cents.
IMHO it is a waste of money to try to buy all the support hardware, (emulators, programmers etc. etc. to upgrade the older GM stuff. After all is said and done, you will have spent almost as much $$ and still not have the capability you need much less want.
Ease of tuning is a must. So, Wideband O2 should definitely be in your plans. Otherwise you are shooting from the hip. Real time operational calibration also fits in the must have category. The hit and miss tunning cycles requiring burning proms will drive you to drink. :suicide:
There are other nice to haves that I have now come to believe are also necessary, like dual fan control, Sequential injection, Dual fuel maps for economy and performance, future NOS capability to name a few.
If I were in your shoes, I would consider going with something like the Accel Thruster ECU, (Which is upgradeable to Gen VII btw) and a LC-1 wideband O2 system. I would rewire your existing wire harness to adapt it to the Thruster ECU to save money on a new aftermarket harness. This is where you may have to spend the money if you don't feel comfortable doing cable rewiring. Accel gives you a detailed system schematic for guidance.
your probably looking at ~ $1k - $1.3k after all is said and done.
I know there are a lot of people who swear by MS, but for my money, its not worth the investment. It is, however, a great EFI learning approach it you want to invest the time.
Bullshark