Two Barrel to Four Barrel Upgrade?

I put an 850Thermoquad on my 318 and it ran gangbusters.
But I used a small-port intake.
My guess is that the Secondary Air door just needs adjusting. And or the ignition-timing is late.

Here's what I would try:
check the air filter housing, and
check the firing order, and
Make sure that the choke cannot come on with the engine warmed up. Tie it open if in doubt. Then;
set power-timing to 34 *at whatever rpm it takes to max this number out, Ima guessing 3600rpm, and
Defeat the secondaries, and finally
Roadtest her.
If it now works great, then we just have to fix the Secondaries.
But if it still has problems; then
I would recommend a proper compression test, and
You may want to check the New dual-exhaust to make sure it really is free-flowing.
After you get it working as a 2bbl again, THEN you re-connect the secondaries and roadtest it s'more.
Finally, make the choke work right.
IMO, That's a great induction system for this combo.