SOunds like a overhaul is quick order. However there is a couple of things you might try if you just got to run it some more. a product called Engine restore has kept some of my old tractors going until I could shut em down for a week or so. And another trick is to put in some heavy wt oil. as in 50 lb. But these are only to get you by a few hundred miles. If you lose an insert on the crank and it wears out the crank, then throws a rod, you could trash the whole motor. So my real advise is to have it overhauled now. I just did an in frame job on my 56 F134. Spent about 270.00 total with me doing the work. Took me about a week of working on it after work. And I don't consider myself a real pro with wrenching. I enjoyed the process.