'76 400 in a '73 duster

Fairly new to the forum, but wanted to throw out our build and see what you guys think will be the end result. Like the posting title says, it's a '73 duster with a '76 400. The 400 is out of a truck, low miles was a daily driver until the guy wrecked it. The duster is a factory /6, with lots of cancer most of which we have cut out and welded in factory patch panels from a '74 feather duster and '73 valiant. But more important of course us drivetrain. So what we have going on is this, edelbrock aluminum intake dual plane, edelbrock 800cfm carb, mallory unilite dizzy, msd 8.5mm wires, hughes whiplash cam, new bearings, 516 heads, fast recovery lifters, 4 degree timing set, shorty block hug headers. Otherwise stock bore, rods, crank etc. Putting it in front of a 727 out of a '70 383 sport fury (which came with the bent rod 383 engine and radiator) using the 8 3/4 with Richmond sure grip 411's (yes a chevy ratio), leaf springs and torsion bars out of a 340 duster. Fired the engine up on our start stand, set timing and did all the adjustments. Runs strong, good idle. You can feel that thing rumble the earth. My question is: what do you think it will lay down for 1/4 mile times and what kind of hp. I know from reading other posts on here, the heads suck, low comp, low deck block. The 383 we got after building the 400, which is why it isn't the one we are using, it's going to be built and stuffed into our '74 Javelin. That said any thoughts? The 400 is the one in my avatar.