I have one question...
Is the compression difference in the heads or in the pistons? I don't know a whole lot about these engines, but I do know that you can change the compression ratio in a 350 simply by swapping out for a different dome configuration on the pistons or by different combustion chamber designs (ie. bigger cc for lower compression). I am just wondering which they did to lower the compression on these engines.
Oh yeah, why exactly are you getting rid of this set? Generally speaking, you would just do the work on the set of heads & intake that you have. I can understand having a separate set so that there is no lag time between disassembly, port/polish, and reassembly... I guess what I am trying to say is what condition are these heads in. How many miles are on the engine?
I don't mean to be a dick, but these are all good questions to ask before dropping $200+ on heads that after careful inspection may be worthless.
Questions that should be answered are:
How many miles do these heads have on them?
Are the valve seats replaceable?
Is there any wear in the valve guides and are they replaceable?
What condition are the valve seats in?
Are they cracked?
How do the valve stems look?
Ofcourse you can not answer some of them until you get the heads that you are selling off of the engine but they are still good questions. However, the first 3 can be answered by simply looking at your odometer and the second set of heads that you currently have.