Two things to add here:
1. I used a set of CompCams Pontiac rockers a few years ago. The pushrod length required to get the geometry I wanted, was longer than expected. I have a set of Crower rockers sitting around, which have test-fit about the same as Harland Sharp and PRW rockers on various motors - so I tested them against the Comp rockers. The Comp rockers required a pushrod 0.300" longer than the Crower.
2. I recently built a motor with a set of (owner supplied) PRW aluminum rockers. Using the "half lift" method as well as my version of the "centered on the stem" measuring, I got the same pushrod length. Speedmaster heads, PRW "1.65" aluminum rockers.
EDIT: NO IDEA why the photo is sideways on here, it is not that way on my computer.
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'73 T/A (sold). Low budget stock headed 8.3:1 455, 222/242 116lsa .443/.435 cam. FAST Sportsman EFI, 317rwhp/385rwtq on 87 octane. 13.12 @103.2, 1.91 60'.
'67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 (108LSA/ 109 ICL)solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 w/ old UD 288/296 108 hydraulic cam] Feb '05 HPP, home-ported "16" D-ports, dished pistons (pump gas only), 3.42 gears, 275/60 DR's, 750DP, T2, full exhaust
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