HELP! I bought a mess?

I really appreciate all of the responses. This is great information. Here is an outside the box thought. I have the early 360 heads with 273 adjustable rockers and the LD340 intake. I have a 2001 360 magnum whose short block is good (still has cross hatching on the cylinder walls and great compression prior to disassembly) but the heads are trash (cracked as they tend to do) and the cam is very worn (grooves from the roller lifters worn into the lobes). Is there a way that these parts could be combined together to create a working reliable cruising motor on the cheap?

I say use your Magnum short block and flex plate, and get some CH318B Engine quest heads and a solid cam and lifters then use everything else from the LA motors.
Your LD340 will fit those heads and will work great on it.
Then you can learn what those adjustable rockers are about.:D