what heads to use?

yes I know the casting #on the side say 340
someone went thru the motor before why they changed heads is beyond me. I had the 73 360 on craigslist and a guy called on it. and head asked about the j heads i didnt know about that till then. so I lookd and compared it to my 340 and saw the casting numbers I guess im not letting the 73 360 for $150.00 uh
so I'll check out both set of heads this weekend for cracks and valve size. if the j heads are good and there not the 202 valve they can be machined to be a 202 right ?that is got to be cheaper the aluminum heads