Speed 3 to 6 swap

Hi all!
Trying to dig up some info on swapping the speed 3 engine into a speed 6. I have a speed3 ATM but the body is all beat and it's salvage, I have an opportunity to pick up a clean title speed 6 that has some motor issues. My speed3 engine is healthy and still got lots of life left in it. My question is how hard would it be to swap my speed3 engine into the speed 6. I know for the most part they're almost identical (?) engines, but is it worth doing it, and what all do I need to be prepared for, what will fit or will need to be redone? TIA

 

Bought a bad motor 07 speed 3 with engine out rebuilding it and reinstall. Also did a 06 speed 6 rebuilding a engine reinstall back into the crappy chassis. Then that engine/flywheel/clutch I transfered into another much better 06 speed 6. Engine and clutch alone are same in my experience.
Radiator inlet outlets on engine same. Engine block - power steering mounting points & AC compressor same. Engine to transmission interface bolt patterns and flywheel and pressure plate same. Intake manifold / throttle body same.
Expect $$ on things that come up, so better factor your desires of time and money then triple it. Do I regret my experience of two speed 6's and one in great shape and the other in pieces, one blown motor, bits and pieces salvaged and swapped into "my new 6" absolutely not. Would do it again.
Now both my 3 and 6 are very different animals and will keep both...but... If I had to have, one and only one - it would be my go-cart 3.