As far as the miss, have you checked the valve adjustment? If a valve is a little tight, that could be the problem, and it is more common than one might think. A tight valve won't 'hammer' but can cause loss of compression, resulting in a regular miss, you didn't state if the miss is regular or irregular. Something I like to use is a cylinder leakdown gauge, this gives a world of information on the condition of a combustion chamber. If you have a 'Harbor Freight Tools' near you, they normally stock this tool, but, you will need an air compressor to use it. It comes with instructions, I had to buy an adapter from NAPA, as this tool only has 'modern' adapters. Also, if you buy this tool, I would suggest that you invest in a cheap stethoscope. It is easy and simple to hook up this tool, then listen to the exhaust pipe, carburetor, and thru the dipstick hole to diagnose where there may be a problem. Did you check or replace the breaker points, and condensor in your distributor? Those are good tractors, if you get it running correctly you will be well pleased with it, it will run as smooth as silk.
Take care,
Andy