Welcome to the site man. Planned mods sound good--but for FI on a 5.3L, I would keep the stock heads and clean them up, balance a new valvetrain on them, and do a 5-angle valve job. Then have them decked slightly--but nothing to major which would increase the compression ratio. A live custom tune would be the best, but even a mail order custom tune is waaaaay better than a Diablo handheld POS...