I'm sure that many with different experience than mine will chime in but since a stock head GMC has shared ports and an uneven firing order direct port mechanical injection complete combustion is only possible in cylinders 3 and 4. With the other 4 there will be 2 lean and 2 rich due to the fuel continously going in and having different pulse sequences. I would see no problem a throttle body like a Holley or the ones Moon has made from 97 lookalikes.
I have used 2 different mechanicals both Algon units converted to Hilborn/Enderle style with fair results but never as good as a carb yet. Without unlimited dyno time I have not had the time to perfect injectors on gasoline but I'm sure others have. Nitro or methanol works well or as good as can be expected.
A good computer controlled timed injection should work well and I'm sure there are computer programmers to make then work..Good Luck
216.158 MPH 12-Port 302 GMC on 70% 171.0 MPH 302 stock head on gasoline 7 years later
