65 barracuda no bottom end need opinions

Sit back fellas this story may take awhile. After my 73 challenger burned up I bought this real nice 65 cuda 273 auto 3.23 with nos. what a dog!! Has an edelbrock 600, performer rpm intake, 360 heads small valves and had a comp. 550 lift 244-244 duration solid roller. Fumes could kill a mile away. My shop guy did the computor program and said comp. was about 7 to 1 with those heads. Plan--milled heads .080 also intake side to match intake would get me 9.3 comp. standard gasket. Pistons if I remember .050 in the whole. Pulled cam replaced with comp. hyd. 474 lift 212-212 duration still using adj. rockers. Fumes much better!! 2500 stall. Likes 14 deg int. 38 total timing using vac advance. Even tried 3.91 gears, still won't turn tires when power braking . Re checked lifter preload after breakin and 50 miles running, all good. Has 1 5/8 shorty headers, 2 1/2 ss exhaust, stock size tires. Has 13in. vac at idle, distrib. hooked to port no vac at idle, tried man. vac no diff. Oh I did remove the nos didn' t do much for it. Looking for opinions, my responce might be slow as I am doing this at work and money is short. Thanks All--Mark