Kantor Brothers or google a local rebuilder . We had one here but he retired last year. There has to be others.
Go over to the Ford Barn with your question, you will get multiple answers. One name that comes up often over there is Skip Haney?
I've used Skip twice for non repopped OCM Merc pumps. Excellent work, IMO. If you want another option, Daryl Fryer also does flathead pumps as did his father before him. From what I understand he advertises in the V8 Times. He is in my hometown and I thought about using him since he was local but at the time his turn around time was much longer than Skips. Both about the same price. Skip's web site: http://www.fordcollector.com/water_pumps.htm PM me if you want Daryl's contact number.
I bet Mac VanPelt could sell you a kit to do it yourself, or a new pump. He has good stuff, not the cheapo junk.
I just got a pair of pumps from @Mac VP . New bearings and seals, high flow impellers.. Great price and very reasonable shipping. And awesome customer service!!! Chappy
Yep, VanPelts just sent my dad a pair of pumps for his F3 truck. Helpful people on the phone, and shipped them out super fast. Had him set up in no time.