904 race build

It's the same one I bought new in 1992 that came in a tci box but had j.w. scribed on it.So I was told it was a winter's rmv.

In that case I would be all over Google looking up those names and numbers to find out exactly what I had.
It sounds like what you want to do is up the line pressure, and doing that on a reverse manual valve body should be simple.
On any other valve body can cause a bunch of other problems.

You might talk to TCI first.
You never know, they could be bored during this whole virus thing and give you a lot of useful info.