1969 barracuda 383 formula s temperature/timing help

Also try 10-12 even up to 15 initial...800 to 900 rpm idle. Is it otherwise stock?
I can check the FSM when I get home.

What kind of carb is the new carb? Here is an article on carb tuning you might find useful

www.allpar.com/fix/carb-tuning.html

Edit: The FSM says TDC for Manual 2 BBL and 4 BBL, and 7 1/2 BTC for an automatic. I suspect the BBs respond well to a little more initial. My SB 340 likes more than 5 BTC initial, which is what the FSM calls for.