Coupe

If the costs of the cheaper alloy heads is close to rebuilding the stock heads, then the weight alone would make the swap worth it even with the same flow and HP numbers.

Diputado

For what it's worth....about 30 years ago (yeah, I know..a long time!) I ran 1969 model 351W heads on a 289 in a '66 Mustang. They were flat-cut .040 and also angle-milled .062. I also used TRW 12.5:1 forged pistons, but don't really know what my final comp. ratio was, but it was pretty high. Needless to say..I only used premium gas, which back then was 96-97 octane.

I did have a few valvetrain issues, such as broken rocker arms studs (due to really hot cam) and a dropped valve once when I missed 3rd gear and revved past 6500 rpm (BIG whooops!!!). If you go with the 351W heads, I do suggest beefing up the valvetrain and don't forget that little intake gasket issue with the water passages. Make sure you use the right gaskets and good sealer. Given today's crappy fuel...I would also not mill the heads as much as I did back then!