Get the CR as low as practical. If you are using OEM LT1 heads this will be limited by the small chamber size. JE/SRP has a stocking -31cc “blower” piston that will get you in the high 8:1-9:1 range which is compatible with ~10psi on pump gas. With some decent porting on the heads, a good cam, water injection and/or intercooling and a set of headers this is good for ~500rwhp on a typical LT1.
This much hp will also necessitate upgrades to the drivetrain.
Procharger for the win :tup: all else are inferior :gotme:
As far as blower brands, in my experience both Procharger and Vortech are pretty comparable. I have had personal as well as indirect experience with both. Both of their kits for the LT1 have really marginal intake ducting (upstream of the blower). They use semi-rigid tubing which tends to collapse and cause a significant intake restriction, which centrifugal blowers really hate. An advantage to the Vortech is that there are people making off the shelf rigid intake ducting to solve this problem. I am not aware of this being the case for the Procharger, though there certainly might be people doing it now. It can be quite a chore to fabricate the necessary parts - it you aren’t a mad skilled weldor and have to pay someone to fab a custom piece figure on $3-400.
What cam would be a good match for the vortec or procharger kit?
Camshaft will depends on cylinder heads, cubic inches, powerband desired, etc…
Absolutely! But in general, an LT1 blower cam should have at least 10 degress more exhaust than intake duration. IF you are dealing with stock heads (not ported) there is no point in going beyond 220 degrees intake duration with lift in the low to mid 0.5" range. Way back when I was running an S-trim with stock heads I tried a couple of cams and found that the one which worked best had ~215 degrees on the intake. If you want details, send me an email or a PM.
In my earlier post I alluded to headers. A good exhaust makes a huge difference on a blower car. In my case, I saw a gain of 40rwhp going from stock manifolds+stock cat+Borla to mid length headers with dual high-flow cats and a a cat-back system back when I was running stock heads.
Rich is right. Exhaust is key. I am running about 8psi with an S-trim (hot air) 355, AFR 190’s, LT headers, and a 224/236 cam. I am loving it.
If I had to do it all over again, I would go with Vortech. Sounds great and pulls really hard. The non intercooled part sucks, but I have an alky kit begging to go on.
haven’t got to dyno it yet 
How is your tranny and rear end holding up with that combo?
I had the tranny rebuilt before I put the s/c on because it was sticking in 4th gear, but no issues since. T-56’s are tough suckers. I have ripped a clutch in half, but that happens when you do a 5k rpm clutch dump on ET streets 
The rear end is fine, stock 10 bolt with stock 3.42’s. The car has almost 140k on it. I have not subjected the rear end to sticky tires much though. I just got my MT radials mounted on my prostars about a week ago, and I haven’t done a hard launch on them.