[ar0ck]

Originally Posted by Slow Z

You'll more than likely need to have the heads machined to accept the 1.32" LT4 valve springs.

According to gmpartsdirect.com, you dont need to machine anything.

This off-highway camshaft kit has the major valve train component to convert production LT1 engine for showroom stock racing, or hop up your small block Chevrolet V8 that was originally equipped with a roller tappet camshaft. The 1.6 roller rockers, light weight valve spring caps, special designed valve springs and hot camshaft offers a significant gain in horsepower at a reasonable price. This kit includes the following items: one camshaft P/N 24502586, 16 roller rocker arms kit P/N 12370839, 16 valve springs P/N 12551483, 16 valve caps P/N 10212808, 16 valve keys P/N 24503856, 16 valve spring shims P/N 10212809.