I have decided to do a Cam swap to better fit my application. I have searched and it seems I find conflicting or incomplete information. I have other projects going on with the car that involved removing the intake and radiator. So, why I am sitting here, I am going to go ahead and do a cam swap. Engine has 60K miles, strong compression, and runs great (After the EBL swap). It does have a Vortech Supercharger on it.
I am port matching the factory plenum and base to a set of AS&M runners, so the RPM range can extend more. I have also seen flow results on the 083 Castings and seems a lift of .480-.490" and diminishing returns above. However, I see some sources say the factory heads will take this much lift and others that say .480" is max.

I would like a Cam in the .480-.490 Lift range with around 210-213@.050" intake and 215-218@.050" duration with a LSA>112 I find a couple of options, but I can't seem to find clean data on what can be done without removing the heads and doing machine work.
How much lift can my factory heads take?
Will I need new springs? What is the spring pocket diameter?
What do I need to know about placing a set of aluminum body full roller rockers on?

Thanks for the help. I tried searching but couldn't seem to find the right thread to separate information as stock versus what can be achieved with machine work.

 

In totally factory trim, with factory springs, factory retainers, factory seals, etc., something a bit under .500" is the limit. IMO the difference between calling it .480" and .490" is trivial; a genuine case of measure with micrometer, mark with chalk, cut with axe; the tolerances and variation in all of the things that go into that, plus "assumptions" about things like how much lift gets lost in the stock stamped sheet rubber rockers flexing, or machine work other than the factory's, or even the sloppy factory machining (after all, they only make it "good enough" for what they're doing, and in the mfg world, making it any better is a violation of one of the TIMWOOD parameters of muda, (yes look it up Muda (Japanese term) - Wikipedia you'll gain considerable understanding of what factories in general are concerned with), TOTALLY overwhelms the difference. I mean, JUST ONE valve job on the heads, moves the valves more than .010".

Stock spring pocket accommodates 1.25" springs, nominally.

Just because the flow of the heads stops increasing after .xxx" doesn't automatically mean that you want a cam with no more than .xxx" lift. After all, a cam with higher peak lift but a similar duration, will open the valves MORE at other points in the valve cycle than the peak, as well. A cam with say 210° intake duration might only be within .025" of peak lift for maybe 10 or 15° of that total opening; but if it's an aggressive ramp, like the best aftermarket cams have, you want AS MUCH lift as possible at the durations OUTSIDE of that narrow peak band. Limiting yourself the way you are talking about is counterproductive.

Run stock LS6 valve springs or upgrades to the same such as from Texas Speed or ws6store; the Comp "adapter" retainers 787, and the keepers that go with them; set the spring installed height as close to 1.75" as you can, on the high side (like, 1.76"). With a blower you need more exh duration, compared to int lobe, than you would N/A, since you have help (blower) getting stuff INTO the chambers but no corresponding help getting it back OUT. 5° isn't enough split. Look at something about like the Comp "304" grind https://www.summitracing.com/parts/cca-08-304-8. Use steel body roller-trunnion rockers (NOT aluminum, NOT "roller tip").