98's will definately be real Vortecs,, but still I'd DEMAND a flowbench report on every runner before and after,,,,
Stock L-31 / 855 vortec heads flowed a best of 239 / 147 @ .55' lift measuring 5 different sets on a Superflow SF-600 (it doesn't get more repeatable than this)
* note heads had guides milled for lift / retainer clearance
One set after a home port/polish and bowl job went 230 / 160,,, ohhh yeah nice job!!! Spend days and $100 on tootsierolls to make a set of decent heads WORSE!!! It's a common achievment! Not that this guy doesn't have a proven program for the vortecs, just saying be CAUTIOUS what and who works on them.
Make sure they are pressure checked for cracks before spending anything else,,, and get a real and final cost for:
replacing the guides and cutting them for retainer clearance,
new valves,
seats as needed,
new springs,
surfacing,
and if milling to reduce the chamber the chamber more than 8-10cc (typically around 0.080 to .100") have the intake face corrected
but FIRST, make sure this isn't the 305 vortec heads,,, There is a tiny 54cc chamber version (the 520 casting as I remember) that will net you compression WAY over pump gas toilerable.
I think what everyone is trying to tell you is it is EASY to stumble here and have a pig in a very expensive dress.
The 15 year old castings are showing signs of being an aged lightweight casting.
Roger Rule #2,,,
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Make your choices, Spend your money,,, live with the results.
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