Slant six Holley 2280 stalls when stopping

After I replaced the gaskets I adjusted the screws to 1.5 turns. Ill give that a try.
Any ideas to check fuel pressure other than a tee in the fuel line? Im looking for a brass tee to fit the fuel line and a vacuum gauge.
The only way to check fuel pressure is to tee the line.
What is your initial timing set at?