Thanks for the comments so far. I started a spread sheet today to get a better guesstimate at weight (and cost). I think it will be hard to get this under 2000# without driver. It is tough to get a decent motor weight, I haven't pulled it from my donor car, but from what I can tell the aluminum Modular motors are within 10 pounds of an aluminum LS. Once I pull it, I should be able to get a better estimate.
The motor choice was mostly based on dollars per HP per pound and I am too far down the rabbit hole for a different option at this point. You can't beat getting a running almost driving (transmission slipped) car for less than $500, add $400 worth of cams and valve springs, do some porting, re-flash the ECM and have a 340+ HP and rev to 7200 RPM. The donor also has all the accessories, fuel system, radiator fan, diff etc. to get it running in a hotrod.
Not much to look at now, but move the coils to the back, get rid of all the plastic airbox stuff and polish the 16 intake tubes and valve covers and BAM.
28 spline 8.8, aluminum housing
Believe it or not I am familiar with how small hot rods are. I helped build a couple in college, and we drove 2 very traditional rods down to Speed Week from Chico in 2004. In my opinion, the engine compartment space (without hood sides) is not the problem, foot well area is usually sacrificed due to transmission and bell housing placement. Driver placement / ergonomics will not be sacrificed in this build. I am probably going to split the cowl and widen it a couple of inches so the whole car will be asymmetric and biased toward the passengers side. No hood side on the passengers side, with a pile of snakes 180* header hanging out the side.