Idle vacuum and power valve!!!!

[americanmusc1e]

Ok I just put a new 388 in my '70 C10,

it has a XE 268 cam, and a holley 600 vacuum secondary carburetor

right now it's pulling about 5 inches of vacuum at 600rpm idle, it has the stock 65 power valve in it and the power valve is open at idle.

what is a good Idle rpm for this cam (automatic transmission)???

what is a good ignition timing setting (at idle w/vacuum advance disconnected) for this engine????

do i need to change out the power valve to a smaller one???

or am I doing something wrong????

here are the specs:

home-ported vortec heads
weiand stealth vortec manifold
holley 600 vacuum secondary (4160)
flowtech 1-5/8 headers with full dual exhaust
scat 3.75 stroke cast crankshaft
eagle H-beam rods
.060 over hyperecutec pistons
comp cams XE 268 cam (part# 12-242-2)
stock HEI distributer