Help settle an arguement!!

Aside from a couple of issues, I'd think you're in the ballpark.

Leave the windage tray off if you can, you're much better off with a baffled pan.

That Air Gap knockoff is a piece of crap. I'm guessing I found 10-15hp switching to the real thing. Ports are mismatched, runner shape is bad and small, casting is not good.

The Thermoquad is a confusion factor over the holley. Who knows on that?

My Ford 302s went faster with 1-3/4 headers than 1-5/8. I think the bigger motor can handle the bigger header too.

If you're rating the compression at 9:1 because that's what the factory rated those engines at, its somewhat optimistic. The heads are a couple cc bigger than the claimed 59 cc, and the pistons are about .050 in the hole. You can pick some of that back up by going with the skinny head gaskets that Mopar and Mr. Gasket sell. Worth taking the heads off to check for cracks anyway. My magnum was under 80K miles and both heads were cracked between the seats.

I'd say you can't be too far off, at least with the real Air Gap, unless the thermoquad costs you horsepower over the race carb mopar no doubt used to get those numbers.

The calculators rate mine about 420 @ a race weight of 3400 lbs (through the Super Turbo mufflers), but I know there's more ET in the car with the right gears. Sometimes those calculators are optimistic though...

Mine is probably too different to make a reliable comparo but here's the combo.
I've got the EQ magnum heads, a kevko pan, 1-5/8 headers, Eddy Air Gap (LA), Quickfuel 750, 224/230 .536/.544 cam. My shortblock is around 70K miles, straight out of the junkyard - never even checked the bearings.

Good luck with your Magnum!