A running 235 from 54 or early 55 would be virtually a drop-in swap. Later models have a different water pump location that causes some hassles with the placement of the fan, but that can be corrected by an adapter plate that relocates the pump position and uses the early style pump (like the one on the locked-up engine). A parts wanted ad here, or one on Craigslist might be a good place to start. We've got a small herd of Texas stovebolters who would be glad to help you find an engine, I'm sure!
Jerry
