Mercedes Benz repair: Valve job vs total engine overhaul, piston ring, head gasket

Question
I have an '87 MB190E and has 160k mi.  One day it was running fine, then the next, idling just went rough on me.  The mechanic did a compression test and found that cyl 1 had only 75psi idling pressure.  He also did a wet test which brought the pressure up from 75 to 100psi.  I'm planning to have a valve job done on the car but do you think the 25psi difference in the wet test is cause for concern?

Answer
More data needed.
I would not do a valve job on the engine without a cylinder leak down test.
This will show if it is a head, valve problem, head gasket or piston/ring issue.

I hope this is a Mercedes specialty shop, special tools are needed to do either a valve job or engine overhaul correctly.