-This is a bit off topic but who built your motor? Did you get the rotatging assembly balanced to the cheap forged bobweight?
My next thing is dumb the holley 850dp. Thats wayt oo much carb for a 350 any day of the week for a thirdgen. 750 is calling for 100% ve at like 9000rpm. YOu wont rev that motor that high if your using vortec's.
Remove those junk .530 springs and atleast get .550 springs to utilize those vortec heads. That much lift may seem miniscule but ts actually a turning point in a porformance area.
I posted this link twice today. you can get 550 lift springs for less then $32 shipped to your address. Get them, http://cgi.ebay.com/ebaymotors/SBC-C...temZ8026029901
As for the subject of the thread.
A cam to match that intake(Which by the way i wont even start to rant on) and heads(actually did a great job), is really up to the rpm range you want to use.
I'd recomend a range of 2500-6500rpm.
I'm not going to recomend a specific cam, just data that fits together in my head. That setup would take a large duation easily, so 230/240 duration seems ok, and lift numbers of .500/510 seem very plausible for you. This cam will fit your current springs, but as a recomendation, it will better suit you to allow more lift and higher spring rates. More lift allows improvment and larger ratio rockers, and weight of spring prevents valve float.