Who makes most complete slant 6 rebuild kit

I would lean towards EngineTech; known quality pistons and rings for stock. (Silvolite and Hastings)

I used the Engine Tech kit in my 225. EngineTech assembles kits using known components.
Silv-O-Lite flat tops (.040), Hastings moly rings, and my machinist (doing this since 1962) confirmed they were King rod and main bearings. Because he is a business, he could substitute or delete up to 3 items. I told him to not get the oil pump. Gaskets are OK but I couldn't confirm the brand. My machinist said he never had a problem with them.

Roller rockers? I'm a /6 newbie but I don't think I've run across any. The Nascar engines built for the compact series back in 1962 or so, buzzed the 170 to 7000 RPM's but they may have bushed the rockers, can't remember.