Of course you did Buddy but it sounds like your gonna need a block or fix the one you have...probably easier to find another dead one with a good block. New rubber alone makes it more than worth what you paid. I'll bet if you spent the money to completly rebuild the motor it will last until your great great grandchildren are ready to use it!
To me WD's and 45's are about the best bet out there if your going to use the tractor in the field. They are absolute workhorses and if you break something parts are easy enough to come by. Three point hitch adapters are available so you can use modern smaller implements if you want. I find the implements made for the tractors work best though.
More about value. Some time ago somebody here wrote that a tractor is only worth what someone is willing to pay. Very true! When compared to the price of the new smaller tractors like the little JD's and Kubotas the prices WD's go for are a steal. The modern tractors would never hold up to what most WD's have gone thru let alone still be functionl 50 years from now. If something breaks on a modern tractor chances are your going to have to pay someone to fix it. The WD's were designed to be easily fixed. Even the quality of the metal in the old tractors are far superior...they used virgin metals and plenty of it. In comparison I think the new ones are junk!
Have fun bringing your new find back to life.