Thank you for the info! How would I figure out what vintage the heads are? Also, I did a compression check over the weekend and they ranged from 130 psi - 142 psi. Is that within reasonable specs?
If you search around on the heads, you’ll find a code cast into them somewhere, like “D0VE”. It will be four characters long. Ford parts typically use the first two letters of the code to indicate the year it was made - although sometimes a casting may be used for many years, using the same part number. A good example of this are the “E7TE” heads that were on almost all 5.0 motors from '87-95.
C = 1960s, D = 1970s, E = 1980s and so forth. (and you can figure out the decade for A and B I’m sure). The second digit is the year. So a “D0VE” head is a 1970 casting. Yours are clearly marked ‘351’ so you know what type of engine they came off of.
The 69-70 351 heads are pretty decent in stock form, with a good combustion chamber and port design. With additional porting and attention to the valves, these heads were about as good as it gets for Windsor heads until the GT40 and GT40P heads were introduced. After '70, the chamber sizes got larger, resulting in lower compression and the port/valve arrangement got worse until they hit rock bottom around '74 or so. The “smog heads” stayed lousy until '85, at which point, some beneficial changes started to be made, culminating in the E7TE (which are not as good as the '69 or 70 heads) and later GT40/P heads.
Those compression numbers are pretty typical for a mild 302, maybe a tad on the low side. The main thing is that they are all fairly close to each other, and in that regard, it doesn’t sound like you have any glaring problems with rings or valves. When your engine is hot, typically those numbers will go up, too. Also, depending on your cam, overlap may bleed off some of your compression if it’s more performance-oriented. Anywhere between 125 to around 190 might be just fine, so long as they’re all similar to each other.