A pair of 61 lb/hr TBI injectors are good for 205-210 hp @ 85% duty cycle at the stock 13 psi and if they were static, meaning on all the time, good for about 250 hp at most. Most engines run around 1/2 lb/per hr/per hp. 61 lb/hr x 2 injectors /.5 bsfc = 244 hp. Even if you were running a Vortec head and had a very good BSFC around .45 that is still only fuel for 270 hp.
Simply advancing the base timing will also not work very well. The TPI heads you are running like about 34* of timing at WOT not the 38* mentioned above. 38* is for the older slow burning smog heads. With 20* of idle timing when you advance the timing to 12-16 as mentioned above you end up with 32-36* of idle timing which is too much for the mild cam you have. The advance curve is also slower in the ECM than what the TPI heads need. The TPI heads like about 16-20* of timing from 1,000 rpm through about 2,400, then up to about 30* from 3,000-4,600 and finally on to 34* above 4,600. The TBI heads have a substantially different timing advance requirement.
I have been through converting a 305 HO with 14022601 heads to TBI and had to make massive changes to the chip in both timing advance and fueling to make it run correctly. To give the little 305 with the mild 204/214 @ .050 cam and headers enough to drink I had to run 350 injectors at 14 psi.
Finally....I am not even going to get started on why someone would pull the 191/193/810 swirl port heads off and put even worse TPI heads on.
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