Jkirk, you are tough to have installed that GM TBI. I see you are using their 8-pin module and coil, as did I on my 64 slant. Are you using the GM knock sensor? I don't see the module. The knock sensor screws into a SB block drain plug (same on GM engine). I assume you have an O2 sensor. What distributor is that?
For others contemplating this, a direct bolt-up is a Holley Pro-jection TBI on a 4 barrel intake (square or spread-bore, but not original 273 small-square pattern). I have seen them $25 used. The later models had better injectors (flat top). You would have to re-wire the injectors to connect to the GM harness. You could use the Pro-jection ECU, but it doesn't have MAP or IAT sensors, as Jkirk does, so always a bit quirky, though MAP doesn't work well if a wild cam.