I would have to talk to the person that did the enghine work.
I would also use non-deterant, I have been running a WD that the family has used for last 30 years a lot of heavy work. My dad got some deterant oil that was to be non-deterant. He said she smoke like a steam enghine(Rings were seated to non-deterant oil) . Oil is oil that are only a couple -3 companys that make oil ( so make or type is up to you). Deterent may clean the enghine better I say may , I've work on 10 year old cars that where twice as dirty inside than some 50 year old tractors. Change it when you should and try to check it more than you should.
I talked to a lot of tractor people around here, and a few more in the oil buisness about oil and gas. First is the lead in gas that was stop back in the 70's early 70's like 73 . So do you need lead in gas ??, guess not. But it does, make more octane and lubrication in the enghine. She will run better. Ok back to that lubrication, ( enghine oil) how was the valve system made in your tractor ? I talked to a guy this is all he does is work on old tractors, He says no valve boots or seals for the valve guides. That they were made to get oil down the top of the valve to the valve, they may get all oil baked and dirty but in most case they still work and are still good in older tractors. He has seen a new rebuild head wear the guides in a few years, and the only difference is the boots or seals. Valve system is about the only place I would say to that it is a must to use Non-deterant oil, Talk to the person and see how the head was worked on and go from there.
Have a Good One !!