Tips for HP gain?

Hi guys, i wanna get the most HP out of my engine, what do you think will help the most?
I have not had it on the dyno but it does 9.5 on 1/8 mile with 75 mph over the line. (with bad traction).

Engine: 1974 360 .30 over
heads: ported 596 J-heads 1.60/1.88 valves
Compression: 9.5:1
Cam: Xe274-H flat tappet

Duration @ 0.006": 274° / 286° Duration @ 0.050": 230° / 236°
Max Lift w/ 1.5RR: .487" / .490" Lobe Separation: 110°

Intake: LD340 edelbrock
Headers: dougs D453 1-5/8 Inch
Carb: 670 vaccum secondary holley.
Cooling: stock waterpump, 1117 flex a lite 6 blade ''race'' fan.
ignition: Stock electric ignition all around w/orange box.
Fuel delivery: stock replacment mechanical.
Timing: 35 at 3500 rpm.

Unrelated to the engine hp:
3:23 gears in a 8 3/4 sure grip, 727 manual shift, 3000 stall.

Car is a 1969 dodge dart GT.

Let me know if i forgot any info.