I have two compression gages, both the same make and model. One reads 25 or 30 psi lower than the other. So, don't place too much value on the number, as gages can be wrong.
consist numbers between cylinders is what you are wanting to see.
However, don't except much pressure, especially if you there is a bigger cam than stock in there. The stock compression for a 454 with 781 heads and flattops is around 7.75:1 cr. Then the bigger cam with the later intake valve closing point will reduce cylinder pressure even more.
I would except to see 110 to 125 psi numbers.
This engine will like lots of initial ignition timing. I would use 20 initial, 40 total, and add another 10 degrees from an Adjustable vacuum advance canister (crane: summit racing) connected to a manifold vacuum source. So the timing at idle will be 30 degrees (20 + 10) and total when you rev it up will be 50 (40 + 10).