I like agreeing with Alex. mostly what I was about to say when i clicked on the thread. screw ups are cheap on those. parts are cheap and there's tons of info. tolerances are a bit more loose for old engines.
VW engine rebuild. not my first choice... what with having to heat the pistons up to a certain temp either for measurement or fitment. (I believe that was one odd thing)
Carb rebuilds are nice to know... industry is in real demand of people that know electrical. and its really not as bad as you think.
if you want a challenge, rebuild a 99' era Toyota 4 cylinder. factory over and under size bearings and pistons for precision fitting.