Stock exhaust manifolds vs headers

IDK what you should do;

But
with your other go-fast goodies, and
pistons up a lil higher than the deck, and
if your cam has more that 30* of overlap, I know that
I (me) would install long-tube Headers, like the Tri-Ys, into a long Transition, then
a long torque-tube, into one long, glass-pack-style muffler with NO reducers; then a whatever-fits tailpipe more than ~2"dia, with possibly, another glass-pack resonator on the cold-end beside the gas-tank, ending, finally, in a rectangular 340-style tip.

If I was on a budget,
I would do this before I bought the 4bbl kit.
But then.
if I was really on a budget,
You guessed it,
I would just install any old SBM/A904/2800stall, for way less money spent, and way more horsepower to burn.