here are the basics of my friends 383 that is going into his '68 Z/28, it is a old (RHS) Racing Head Service built engine.

Sportsman 200 heads (2.02 & 1.60 valves, 64cc)
5.7 rods
3.75 scat crank
blocked decked to .000
fel-pro head gasket .041 x 4.166
18cc dished pistons (comp. ratio w/64 cc=9.7:1)
750 holley dp
mallory ignition
original Z/28 intake
hooker headers 1-5/8"
4 speed
3.73 gears

originally, RHS installed a 292 Lunati cam, the intake valve closes at 73*, the DCR will be in the low 7's with this cam, Is there another cam that would do better?
I know Comp Cams close their intake valves sooner, this would bring the DCR up.
Any ideas?

I go with an agressive lobe that has no more than 280* duration on the intake. Something like the Comp XS282s would be my pick.

What are you friend's plans for the engine? Mostly street, mostly strip, etc?

xs282s, I agree