If you look on top of the post, I just got the car back from tuning. Timing was of course also checked.
I don’t see an engine size.
If it is a 302 and your pistons are not flat tops you need to mill a lot off of the heads.
If it is a 302 with flat tops you need to machine the heads to 57 cc’s.
You need to measure how far the pistons are down in the bore at tdc. . you need around .040 clearance between the top of the piston and cylinder head . . adjust this clearance with thinner head gaskets from cometic.
Those heads come with either 1.90 or 2.02 valves, which ones are they?
try a 1/2 to 1 inch spacer under the carb.
Buy a 600 cfm quick fuel vacuum secondary slayer carb or an ss style if you have more money . . the comp cam guy is an idiot 500 is too small.
that is also a horrible cam for those heads.
Buy 8, 1.65 or 1.70 rocker arms for the exhaust.
Set your valve train geometry.
Plug your distributor vacuum advance.
set your idle timing to 12.
Set your total timing so it reaches a max of 32 degrees btdc at around 2600 – 2800 rpm.
1 1/2 inch tube shorty headers will be a little better . . hedman elites are good.
you need at least 3.23 gears, 3.40 would be better.
the mustang dynos read lower than most . . another type of dyno would show around 25% more power.