Gravely 1234 Engine exchange

[gunslinger69]

I need some advice and direction. I have a Gravely 1234 Lawn Tractor with 12HP engine. My current machine is having transmission difficulties where it will only go in reverse. Last year I rebuilt (reface) the clutch faces and along the way transfer broke. I repaired that but apparently had too much pressure causing something to snap. Meanwhile my wife of almost 50 years is thinking I am having an affair with some girl called Gravely. Tomorrow I am going to look at a machine, same model, available locally. Supposely the transmission is good but the Engine is bad (makes some strange sounds when it heats up). My question is : How much effort or how difficult is it to exchange my good engine with his bad engine? Any thoughts would be appreciated.....Thanks in advance............