Burning through coils and can't figure out why

Are you sure you have the proper resistor and coil. If it is inded a GM engine, you will be able to find an engine code on the block. Use this number and do some searching on the web. Identify the motor and the nomenclature or designations and applications it is used for as this will help you to find parts for it. See if you can find the model of forklift while lookking at applications for the motor. Search any numbers that will help you find information on the forklift. You may have a, "Frankenstein" forklift that someone adapted the engine to work in it somehow. I have seen stranger things. You need to find out all you can by finding an identifying marks on the forklift and the engine and search the internet from there. It is the largest database that has ever exisited and grows at a rate that is contantly increasing itself with information on the most obscure of information that can be had. Information is the key to all things and the internet is the way to find it quite easily.
I cannot give you any more guidance than this as it is what I would do in your situation.
I hope it leads you to what you are looking for and solves the problem at hand.
Take care and good luck.