Here are a couple of good authors of books on how to restore a farm tractor.
As others have commented, vintage tractor values are on a downward slope although the recent surge in farm income has temporarily bumped up prices. Thirty years ago your Farmall C was a great candidate for mowing large lawns, today zero turn mowers are a better choice.
First determine how you will use the tractor when it is completed and what your maximum budget is. then evaluate what this tractor will need. It was parked for a reason, find out what was broken back then and add on what has deteriorated since it was last parked.
You will probably spend many times more to restore the tractor compared to buying one that is already field ready or a completed restoration. Spending $1,200 for tires, $2,500 for an engine overhaul, plus clutch, transmission bearings, paint, radiator, missing parts, etc. adds up fast on a tractor that can be bought in running/restored condition for under $2,000.
If you are looking for a project to burn off some extra time and cash, go for it and have fun.
How to Restore Your Farm Tractor
by Robert N. Pripps
Format
aperback
Language:English
ISBN:0879385936
ISBN13:9780879385934
Release Date:January 1992
Publisher:Motorbooks International
Length:176 Pages
Weight:1.25 lbs.
Dimensions:0.4 x 8.3 x 10.6
How to Restore Your Farm Tractor: Choosing a tractor and setting up a workshop - Engine, transmission, and PTO rebuilds - Bodywork, painting, and decals and badging (Motorbooks Workshop) Paperback June 9, 2020
by Tharran E Gaines (Author)
Publisher : Motorbooks (June 9, 2020)
Language : English
Paperback : 256 pages
ISBN-10 : 0760368465
ISBN-13 : 978-0760368466
Item Weight : 2.15 pounds
Dimensions : 8.25 x 0.75 x 10.63 inches