Timing Question

With 145-150 PSI in the cylinders, I suspect your compression ratio is higher than you think. I'd start with initial timing at 10 degrees at idle with vacuum advance disconnected. Check the timing from idle to 2500 and see what the light reads. If you're cruising at 2000 RPM, you'll want about 10-15 degrees of mechanical advance at that RPM. Connect the vacuum advance and see what the timing reads at the same RPM's. At 2000 RPM you won't want more than about 25 total. That reading can go 5 degrees either way depending on your actual compression ratio. It might take a little trial an error to dial it in.