Improving my 360 combo. Need advice/input

Not a terrible combination but could be improved. Performer RPM Air gap if the M1 is the single plane version. This is probably the best overall dual purpose manifold. The Crosswind is a chaper alternative, a Chinese copy of the air gap Summit sells.
TTI stepped headers 1 5/8 to 1 3/4. Expensive but so much better than cheap headers, which will find every pot hole!
If the heads are J catings, the J will be visible in the area around the spark plugs. If they are later heads, there will be sort of a square flat spot cast in.
Casting numbers are on the intake branches, pull a valve cover to find out. Even if later, no big deal.
A light car can get away with a single plane easier, what vehicle is it in?
Keep us informed, we'll try to help you out!
Alan