So I lived to quickly regret not putting that spring in the new manifold.
It started collapsing on me today, which seems to be a very common problem. It causes the hydraulic to be extremely slow when it does, although the steering was fine. It collapses on the port for the accessory pump, and leaves channel to the steering pump.
Took the manifold off, put the spring in, everything is fine! Keeps it from collapsing.
For others looking for an appropriate spring, in my case is about 4 1/2" long, and tapered from something like 1 1/4" (inlet side) to 7/8" (outlet side). It is brass colored, but looks like it is galvanized not brass. Probably some good posts about it elsewhere.