The combo of a 110 * LSA allows too much overlap , long tube headers will create a suction behind the exhaust leaving , in a manifold this is not possible , it will run far better with a 112* lsa or more
While not exactly hard it is expensive , the header / grille support is unique , the front fenders either need to be modified for 4 headlights or use the 71 only front fenders , the front valence is also unique as it has the front park/turn signal lights in the front valance which is unique to...
I would weld in extra support in the steering box mount then powder coat it semi gloss black , I also did mine .
Triangulate inside the steering mount .
8 PSI can over fill the carbs , you should be in the 5.5 PSi range , might need a regulator , have you checked the float height , it has to be done with the car running .
Tuning for sure
Also everything at the rear of the car , trunk seal , taillight seals , any open holes or rust in the rear 1/4 panels or trunk drops inside the 1/4s , you should not be smelling fumes at highway speed at all .