Welcome to CHR:

Welcome to CHR. As you probably already know, the Gen VI was exclusive to trucks. GM made them from 1996 until 2001 so there’s s ton of them out there. As such, there are a lot of aftermarket parts. When you say “crate engine” in the Gen VI it is typically a 290 HP replacement for a truck. There were two versions produced: L29 which is the basic 454 truck replacement and the L21 which has upgraded internals, i.e., forged pistons and crank. The L21 is the better of the two. Both have 4-bolt mains and are roller cam engines. Gen VI also had standard oval-ports with 102cc chambers - so if you have peanut ports; it’s not a Gen VI.

The bad news is this – there is no simple cam upgrade for this engine. As you mentioned, the Gen VI featured a non-adjustable valve train, (like most late-model big-blocks). The folks at GM designed this engine for low RPM and torque so the cam is already ground in that direction. Virtually any deviation from the factory cam specifications will require compatible rocker arms and valve spring upgrade. That said, a mild upgrade like a COMP Cams Xtreme Energy Camshafts 01-412-8 will work, but I’d still recommend valve springs. You definitely do not want a lot of lope at idle as that typically indicates a poor choice of cam. Only kids think the flatulating elephant sound is cool and what your hearing is the engine struggling to stay alive while raw gas pours out the exhaust. The overlap will also kill your low RPM performance.

Another approach would be to ditch the TBI (if your state allows such from a DEQ/smog regulation standpoint) and drop on a Weiland Stelth manifold with an 800CFM Quadrajet and some long-tube headers. I think you’d see a 50HP jump and without tearing into the internals of your engine.

Regards,
Glenn