I would think a new pump would be just fine. If you want a lower pressure a weaker spring in the relief valve/pressure regulator valve in the output fitting of the pump would do the trick.

First find out what the normal, or allowable pressure is on the old system, and what the new pump should put out, may not need to do anything.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-