" fine tune that once you get your timing set while using a vacuum gauge to get the highest vacuum"
OH, PLEASE, stop all that incorrect info about setting initial timing with a vacuum gauge, IT DOES NOT WORK. Timing is set specifications, not voodoo with a vacuum gauge that makes things worse.
With that cam, I'd shoot for 14 deg/BTDC @ idle of 750 rpms. Then, I would connect the MODIFIED vacuum advance into FULL MANIFOLD VACUUM, NOT PORTED.
MODIFIED VACUUM ADVANCE should give an additional 10 crankshaft degrees AFTER the engine starts up, for 24 deg/BTDC IDLE degrees timing, once again, after engine starts. Set carb and idle speed after getting timing/vacuum advance correct.
Vacuum advance modifications: Stop down the advance degrees available, Crane stand alone stop plate will fit any GM vacuum advance, (complete FREE info and pictures package on how to do it RIGHT, ask for them).
The cost for the Crane stop, p/n 99619-1, and the screw and washer to mount them (from YOUR local hardware store) are under $5.00, and YOU install them (drill/tap one hole, install plate, flat washer, hex head screw, trim off excess threaded screw length from underside of advance mounting plate, mount, adjust, done).