I think FPA can help you out.

Windsor Jr's don't suck, they just don't flow as well as many aluminum heads. As a matter of fact, if you look at that comparison, they outflow pretty much anything else cast iron. The downside to cast iron, however, is that it's cast and not CNC'd (cast iron is expensive to CNC), so port designs are limited by the casting process.

 

GT40's work very well on street 302's. 302's don't need, nor do they want large heads. A GT40 won't make the most power but it will run very well, and if setup right can get close. The Windsor Jrs are ok for what they are, but if you want better heads on a budget then some used aluminums are prolly the way to go. Just be careful you don't get a set of heads that are all tore up.

 

Well, looks like my plans just got shot down. I thought the FPA headers would fit, but I just got off the phone with them and he said they for sure will not fit the GTP head, not to mention they wont fit the 65 steering linkage. He said the car he used for mockup was a 64, which uses slightly different steering linkage. I talked to a couple people with some knowledge today and thought I would go with ported gtP heads, a roller cam, and just be happy with whatever horsepower I wound up with (probably around 350). I guess I could still do that but with the non-P heads like I originally thought of, theyre just a little harder to come by and slightly more expensive. On the bright side, I worked out a deal with a buddy so that he will port the heads in a trade for some stuff I have. I have all the equipment to do the valves/seats, so that just leaves me with rocker arms and I know someone else with a bridgeport who should be able to drill and tap for studs so I can reuse my existing rocker arms, leaving only springs to buy.
Im sure this all seems like more work than just buying some used aluminum heads, but I only have a 2500 stall convertor and 3.55 gears which I wont be changing. I think the smaller runner size of the gt heads will give up some big end HP, but hopefully gain enough low/midrange to make up for it. I hope. Plus it will keep some of the stock/stealth look I like.
In looking at the flow numbers, the gtP heads (no numbers for non-P heads) outflow my current Winnie jrs, up to .400 lift on the intake, so I think ported they should be ok.

 

Crap Oh well, you seem to have it figured out.

 

This website has been posted a bunch in the past. It is a good list of flow data for different heads.

http://users.erols.com/srweiss/tablehdc.htm#Ford

Flow @.500 lift
GT40 187/129
GT40P 190/127
GT40Y 212/134
GT40X 238/173

If you compare that to AFR 185s the numbers are not so good, but better than the old 302 stock stuff that is down in the low 100s!

 

Gt40s should have know problem!