Welcome to CHR!

The LT-1 certainly was an incredible engine. The RPO LT-1 motor was first introduced in 1970 (and there after officially referred to as “LT1” no hyphen). It was rated at a very conservative 370 horsepower at 6,000 RPM. As you mentioned it was 11:1 compression (still “doable” today with premium gas) and it was built with all the good high performance pieces in the GM parts box – including a mechanical flat tappet cam. The heads were the #186 castings on the 1970 LT-1's - 2.020 intakes, 1.600 exhausts, and screw-in studs. The high rise aluminum intake was one of the best factory pieces to ever come out of Detroit with a 4160 style Holley carburetor it pushed a fairly heavy Corvettes to14 second ETs.

ZZ4 is intended to be an aluminum headed roller cam engine that is thirty years newer in technology. IMO, it would not be well served with the 1970 LT-1 cam and 186 heads. A complete ZZ4 crate engine would really cook in your 64 Chevelle and would be a good choice (as would any number of crate engines in the $2,500 - $5K range).

If you’re set on building an engine, you may want to also consider a 383 - but definitely build with a hydraulic roller cam. Tons of build knowledge here from Pat McCarthy, Jerry Clayton and others who are more than willing to share with those who genuinely want to listen and learn. Tell us a bit more about what you end goal is, i.e. cruiser, daily driver, bit o’ drag racing and what you’ve got in mind for budget.

Regards and once again, welcome to CHR.
Glenn