Exhaust Manifolds

@Dan the man
BTW,
you can put a 2-speed quick-change in the back in an afternoon . Drive it around all week with 4.11s/4.30s, then, if you need to make a hiway run, just swap the gears for overdrive, in just a few minutes. Yeah it's expensive, but it solves all the problems in just about one afternoon.
It was on my list for the longest time, but ultimately I chose the GVod for more flexibility.
Another good choice is converting to a clutch and an A833 overdrive. The 318 is a good candidate for this; the roadgears would be;
12.08-6.53-3.91-2.85 compare; to the autos; 65=2375, with 3.91s
...........7.20-4.26-2.94 for the TF and cruises at 65=2500 @3% slip.
11.95-6.75-4.30-2.88 for the Chevy, cruises at 65= 2370 in Loc-up.
Notice anything interesting?
Yeah, First, Second, and overdrive are just right. and in your combo, Third will be fine. This swap, in an A-body is about as simple as it gets. about the hardest part is installing the floor hump. I know a guy ............. PM me.