K5 350sbc?

Im looking at buying a K5 blazer, it is said to have a 350 in it, I think these came with 5.0L which is a 305? right? but can you put a 350 in these K5s and what all would you need to do this. and when i look at the shifter there is 2 of them, one is for 4 wheel and 2wheel drive right?

Also what is the best way to tell if it is a 350 and not a 305 or whatever, look at numbers on the engine?

they could have come with ither engine 305 or 350 and its no big deal switching one for the other. if there are 2 shifters if its a standerd then one is for the 4x4 the other is for the tranny.