Both those engines are GM Family I smallblock so the swap should be straightforward as long as all the ancilliaries are available.

But when you have completed the swop how are you going to register it you will require a new log book and I do not think your insurance company will very welcoming plus a new mot.

This swap isn't difficult to administer in the UK, DVLA will change the engine number and capacity and issue another V5C - at that age it'll make no difference to VED class. Insurer will need to be notified and additional premium paid.

Are you sure about that having done it few times its not as easy as you make out nor are the insurance companies all that keen to insure an oddball car.The emission test is rather complicated as no data is available for the MOT testing station to use.