I showed a few pictures in my earlier post.

One had lifters in stock location none of the raised X webbing in cam tunnel area.

Other has the heavy bracing and obvious lifter relocation.

You will have a hard time bolting older heads onto the newer relocated lifter config.
The rocker gear is not stock in the newer heads as you might think.

Again they will get around to providing the new casting with a standard lifter location and the older heads will all fit and pushrods and rockers won't be an issue.

My FS/D stocker has a minimum weight of 3370 with driver as a 392 combo. This combo uses the 6.1 block with cnc'd Apache heads and T&D rockers which requires machining of the head. I believe our best pass at Indy last year was 9.37.

Mike