Not to add to the confusion but I have a set of '576' heads. Mine are 1.88 valve and the rocker stands are stock configuration with 5/16" rocker shaft hold down bolts. They are basically a 308 without the smog holes. I also have two sets of factory 308 heads from hydraulic roller motors, the pushrod holes are exactly the same as these.

Mopar was offering ported versions of these back then. They were calling them high swirl. I looked in my small bock engine book which was from the late 90s. I believe they used the 576 casting but sold them as a package under a different part number with various levels of porting, stiffer valve springs, etc.

Also looked in my 1998 MP catalog and that's even more confusing with all the different part numbers, nothing resembles exactly what you have.

Plus, I definitely don't see anything that mentions modified rocker stands.