Having spent alot of time and energy trying to solve issues on a scud with a mad pilot and now owning a 413 I'd say for me (like to build em extreme) I'd say they are the same the scud has a longer wheel base and generally better body's than the older sami's... the sami body has lots of straight pannels which are easier to fix or modify
The rest of the bits in them well

I don't want to keep any of the bits on mine just the body
If you are not going to swop axles to something stronger then, the sami is the better, stronger drive line, an engine swop is dead easy from pretty much any 4 cyclinder rear wheel drive car as they have a divorced transfercase, the vitara front diff can't handle bigger wheels and lift (lift stresses the cv's, can be solved by some brackets to drop the diff about 40mm, but unless you get a steelcase front diff off a grand vitara (rare and expensive) you will brake front diffs on 31"s..... the bonus of the vitara is there are alot more of them out there, sami's are getting a bit harder to get parts compared to vitara
If 30"s and family drives are the ticket then the vitara is the way to go way more comfortable, better handling
Cheers Reece