WHO'S GOT THE SCOOP ON RESIDUAL VALVES?

Hi Folks

1971 Demon with OEM 10 inch rear drums and KH discs.

I Bought 2 master cylinders for the above application. One MC came with no residual valves and one came with 2. Both mc's have the large and small brake fluid reservoirs.

The system includes original wheel cylinders and original proportioning valve. I plan on using the mc with no residual valves......Should I install the residual valve in the rear brake outlet or leave it as it came.

***On a side note, I have 2 masters from a 1993ish pick up with disks up front and drums in the rear. There are no residual valves in either port on both masters.***

What say ye?

Thanks FABO