I plan on buying the Vortec heads for my 350, but I want more cam lift than the stock valve springs offer. For a street/strip car running up to 5800 rpm, will the upgraded heads with Z-28 spings hold up? The option is to buy the stock vortec heads and have them machined for aftermarket springs (more money). I'm thinking the upgraded heads will be a better buy if they hold up to "spirited driving". Has anyone used the upgraded Vortec heads and what's your experience?

Scoggin-Dickey Performance upgrades the regular vortec heads for use with greater lift I believe.

I put about 25,000 miles on mine with a solid cam, spinning to 6K frequently, 6.5K much less frequently, and 7K once. No signs of valve float.

Here's a link to the cam spec card (http://dab7.cranecams.com/SpecCard/DisplayCatalogCard.asp?PN=113841&B1=Display+Card).

As you can see, the actual valve lift isn't .480 and .500, but .458 and .478, because of the lash.

It runs much better than the hydraulic cam I had in there before, which had the same 278 advertised duration, and a valve lift of .467 on both the intake and exhaust. More power, higher revving, and better gas mileage too. Can't ask for more than that.

Both of these cams were run with the same heads.

I know, it's more info than you asked for, but I thought you might want the whole skinny.

This is with the LT4 springs, locks and retainers, (Not the Z-28's. I only recently discovered that there's a difference. Duh!) The LT4 springs don't have an inner damper, so there is much less need for machine work.

The heads are out-of-the-box GMPP Vortecs with no machine work, and the seals were replaced with old-style umbrella seals.

Works mint with my setup, but I can't promise that you'll have the same results.