cheap heads-free 340 heads on a 360

340 and 360 heads were all very similar. The 2.02 valve versions can flow more but really won't be a benefit over 1.88" valves unless it's more modified, higher rpm combo. If the heads you mentioned are NOS, you will have nice, high valve seats which will flow better over a set of heads that have had a few valve jobs. But I would save them for a better build or sell them to someone looking for a set of NOS heads for a restoration.

I am curious about the casting numbers.

"Huge cam" with stock compression is not a good combo as it will hurt power overall.