[Lanceskene]

Another concern with the heavier engine might be the frame where they tend to crack at the rear.

If it runs, mows, and looks half decent it may be worth buying but without the original engine its not worth much, especially if anything has been butchered. The condition of the tires needs to be considered also because new ones could cost more than the tractor is worth.

Big question is 'How bad do you want one'

IMO... they are cute little tractors that are too small and light to do anything very well, more of a novelty toy than machine with a purpose. If your looking for a toy project fine, but if you need a lawn mower you should find something more modern with readily available parts.