Can a 400BBM w/cheap aluminum heads compete/dominate against the street LS?

Like what you build sir.
An LS engine (6.2 Liter-408ci, LS7 -entry level, but without problems, if 408 stroker built, best probable cam, include their fuel injection wiring harness.-the real top end entry level contenders-allot like the way your family built big blocks!
Well I've built 383 Chevies and 347 Fords but never a LS engine, so..............having no experience to fall back on I should stay out of this discussion.

You should have seen his 361 build in 2011!!
Oh, and...........I've never built a 361, not in 2011......not ever. Now my Dad did build one in 1959, ran over 150 mph at Bonneville that year.