[Bob Pagano]

I am guessing you have a 69 Mustang, it can run the 390 or 428. You can go to the nhra site and look under competition and down load the blueprint and class guide for 69 ford. In them it tells you what head #s are legal and all the legal spec's for each combo. Start there, everything you need to know is in there. Nhra accepted products gives you lists of legal replacement rods and pistons. There are lots of guys on here running those combos, I am sure they will chime in. Have fun, bp