The problem with Trick Flows heads was with the old casting for pedestal mounted rockers. People were using stock 5.0(non-roller tip) rockers on these heads to save money. The lack of a roller tip caused side loading of the valve, which cause valve guide failure. They have since discontinued the pedestal version, and have changed to bronze valve guides as well as changing rocker stud locations slightly.
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67 Fastback - Arctic White Pearl paint
351W ,Trick Flow Aluminum Heads, Edelbrock TorkerII, Carter 750 CFM, Comp. Cam 477/510 219/233@.050, Performance Automatic C-4 Trans, 3.55 gears, Front Disc Brakes, 1-1/8" Fr. 3/4" rear sway bars.
My 351W Fastback