The TPI itself is the same for 305 or 350 it is the injectors that are either 19lb/hr for 305 or 24lb/hr for 350 and then a slight difference in prom programming but you could still run a 305 setup on a 350 and vice versa. I personally have used a 305 injector on a 350 and bumped the fuel pressure slightly.
The bigger question is is this a MAF or Speed Density setup? It appears to be a MAF setup as it looks like I see the ninth injector hole (cold start injector). The system probably came out of a Vette since it has the weatherpack ECM and rear exit fuel lines.

that's not rear exit, that's the ninth injector...just below the middle of the manifold.
You can see the fuel connections above the cooling neck...
agree about being from a vette, 99.9% sure it's MAF