Timing help please

Good Morning All
I went to Sears today and purchased a new digital timing light for one hundred bucks.
I dont know exactly what I should set the timing at.
I disconnected the vacuum line from the distributor, set the timing light for 10 degrees and moved the distributor until the crank mark aligned with zero.
What should I set the timing for
Here are the specs
1976 440 engine
.030 over TRW pistons L235530 10.17 comp
78cc heads
Mopar purple camshaft 284 duration and 484 lift
Edelbrock performer intake
Brand new Holley 750 vacuum sec
Orange ecu box
MSD 6al

Also I checked the vacuum in drive and 600 rpm the vacuum gage reads 5.5
I believe I need to put a smaller Power valve in the carb??

thank you for ant advise
George