Oil pressure and water pipe question

[ckulchar]

My friend that recently purchased the 1928 Phaeton has a few more questions. He'd like some advice on.

There was an oil filter added to the engine. There is an oil pressure gauge mounted below the intake manifold. It reads 2 lbs with motor running. Thoughts on this?

Also there is a tapped hole in the back of the block with about a 3/8" copper pipe connecting to the water inlet. The unit is nearly done. Leave it or remove?

Thanks in advance.
Charley