13's, stock '71 318 short block.

Best thread evar. Sounds like fun. I almost did this and still really wish I had.

Having a good hooking chassis can make a little horsepower go a long way. I had an (ahem) 5.0 Mustang. Bone stock throttle body to pan with some chassis improvements and lightening, went 12.90s with a 4.10 gear and slicks. Car still weighed 3200 pounds with me in it.

You're lucky on your shortblock. My '71 318 slugs were .110 in the hole. Combustion chambers were about 70cc also, but you'll alleviate at least that going with aftermarket heads. I would err on the side of small with the camshaft. Dynamic compression losses with a too-big cam will kill your horsepower. That camquest software is notoriously optimistic.

I'd highly recommend spending money on the converter. Done right, its really cheap ET $$$/tenth wise.

I'd go with a bigger carb if possible. My bone stock 318 was pretty well matched for a 670cfm Holley with that LD4B intake.

Oil control is a cheap place to pick up power. Windage tray and good oil pan (and good oil) are all worth ET.

My '71 Dart 318 car was 3150 approximately with bench seats, 50 lb air conditioning compressor, ridiculous heavy power steering, etc. I imagine you should be able to get it under 3000 pretty easy.