the heads sold by Jerry at PI Motorsports ARE the CHI heads.
With the 400, anything that fits the 351C will work on the 400 as well, the only caveat are the intake manifolds, normally an intake adapter plate will fix that. In the world of alloy cylinder heads, besides CHI (cylinder head innovations), there are AFD (air flow dynamics), all the Ford Motorsport heads (A3, B351, C302), Brodix BF300 (modern version of C302) and a new 2V head promised to be released soon by Edelbrock. Trick Flow is now working on a Cleveland 2V head as well. Don't forget the cast iron 4V & Australian 2V heads either. The 4V head works much better on the larger engine. All of the above heads are compatible with Cleveland pistons & valve train parts.
The first step is to define a budget & an rpm operating range for your engine. The alloy heads are expen$ive. I always suggest a 2000 to 6000 rpm operating range.
George