If the retainers are aluminum, recycle them ASAP before you have to recycle the whole engine. If they are titanium retainers, you're fine.

The blocks were a valvetrain trick to help geometry, usually with long stem valves and/or get clearance for larger diameter valve springs. Milled rocker shaft pads were standard on race W-2 heads. Econo W-2 had OEM-style cast stands.

Double-check the rocker contact patch on the valve to make sure it's not to far inward towards the shafts.

The plate inside may be a Milodon or similar valley tray that has a pair of spring steel straps that snap under the heads. It keeps the lifter in its bore in case there is a valvetrain failure. Otherwise, a lifter popping out could cause rapid oil pressure loss.

The intake looks like an original Edelbrock Torker or Tarantula intake. My personal opinion is that either one is junk compared to what is available today.

I also just noticed that the oil squirt holes on top of the rockers have been closed off with a set screw!

Do the hold-down bolts go through the middle of the rocker shaft or is the shaft offset towards the intake?

Intersting set-up. I'm curious what's inside too!
This should probably be in the Unlawful's Race Only section.