Here's a link to a pushrod length calculator. It's really a cam guide but scroll down to the pushrod section.http://www.ls1tech.com/forums/showthread.php?t=327734

<div class='quotetop'>QUOTE(RedHeartbeat &#064; Jan 23 2006, 08&#58;45 PM) [snapback]42012[/snapback]</div>
The .011" difference at the pushrod won&#39;t be an issue normally. The LS6 had sodium and hollow filled valves to lighten the weight on the valvetrain for a higher revving engine. The LS6 has a higher redline than the LS1 engine.
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So are you saying GM did this to reduce the rotating wieght/mass of the camshaft?