NOS Chevy "factory high performance" 307 engine?

[lowmile]

Anyone familiar with these engines I purchased two early 70's NOS 307's from an old boat dealership along with two NOS 1967 Buick 300 engines. They have deep groove pulleys, LT1 valve cover's, 4 barrel intakes, and also have windage trays. I've found a little info on the web but not much. Any help would be appreciated. Thanks mark