Loopholes are:
Finding a dependable and reasonable shop to do the swap. Are you making the seller to do the replacement of the engine?
Making sure you get a warranty with the swap. Remanufactured engines are a pandora's box unless you have had experience purchasing them. Used engines the same. You need to know what to look for and what to replace/keep.

I agree with 69 and Gorn, if the engine overheated then I would suspect the bearings and heads are also toast.

Not a good prospect for a 1st time project unless you have a lot of time and money.