What year el caminos 73-87 came with 350's, which model, and how do I tell?

[C30Shaka]

topic basically says it, I want an el camino in this year range but i REALLY dont want a 305

what years within this range had them, and specifically which trim models

and how do i tell if its a 305 or a 350

I know to look up the numbers on the stamp on the heads and the plate by the alternator but is there another way?

thanx for any responses