ZDriver.com - Crank-no-start in a 1987 w/ VG30E?

Hey y'all. I'm looking at purchasing a Z31 in my area that the seller has listed for an awesome price. Only issue is, the vehicle doesn't currently start. The crank will turn, and when the key is turned, the starter motor will fight one hell of a battle to try to ignite the engine, but it is never successful. The seller recently replaced all of the fuel lines and fuel pumps, and tested those out. The fuel delivery system is entirely functional. He thinks that the car's issue stems from a blown head gasket, or worse yet, a crack in the cylinder head. I'm not very experienced with these cars, so I'm not sure if he's correct in thinking this. Could a blown head gasket or a cracked cylinder head cause the vehicle to have no ignition? Again, it isn't seized. The crank will turn when you use a large ratchet or breaker bar on it.

My question for y'all is: What is the most likely cause of this issue? Has anybody experienced a similar issue? I'd love to get the VG30E functional so that I don't have to spend money swapping it out, but if it's irreparable, then I'll probably end up swapping for another VG30E or, if I'm feeling ambitious, maybe an RB25DET. On that note, another (very stupid) question: What transmission does the RB25DET take? Could it use the Borg-Warner T-5 that is currently in the car, or does it require a whole different trans? Thanks in advance for the information. I'm also gonna go ahead and cross-post this to zcar.com and see if they have any ideas as well. Thanks everyone!