424 value

I have an 1967 International 424 gas that I moreless borrowed from my brother-in-law for the last year. Well its time to come up with some cash for him. So am wondering what a fair market value of the tractor is?

When I got the tractor the rubber was in good shape, it still has the 12.4x28 visible on the tread. It also has wheel weights.
The sheet is overall in good shape with the fenders in better shape than the hood which has a few dents on the front end. and it was crudely repainted
He had put on a loader that him and his dad made (they are both are in the metal fabrication business). The only thing they had to work with was the main arms of the boom, they made the rest including bucket, however the cylinders on the bucket are too short and need replaced and they had hooked the hydraulics into the quick connects as a quick fix and I hooked in directly in the hydraulic system.
When I got the tractor it was running but poorly because of electrical system. I have done the following to the tractor to get it running without problems rewired the electrical system put on a new coil new fuel pump and this past spring ended up doing some engine work involving pushrods. But nothing major was done to it.

Thank you for your time and all help is greatly appreciated
Jason Sunderland