TH350 pro needed

[rough69]

I'm rebuilding the TH350 in my newly acquired '71 GMC 2500 which was rebuilt but had 3rd gear frictions burnt up and no drive gears whatsoever.

Everything is going smoothly, but when I split the pump halves, the old washer style (#3231580) pump has what seems to be a small valve in the front pump half.

I only found one exploded diagram online which shows what I think is a spring that should be behind the highlighted area that is missing.

Any idea where to find this or what I should call the little (pressure relief?) valve here? Can it just be omitted? Would the missing spring cause failures?

Also the kit I bought gives you new split teflon stator rings instead of steel lock rings like the original pump has. Is it ok to run these or do I need a different steel stator ring kit?

From what I've seen some builders also omit the second sealing ring for "dual feed"? Is this something I should do?