the best motor to rebuild is one that has no rod knocks or bearing problems, but instead has like, a cracked ringland or just low on compression due to bad rings.

if theres something wrong with the crank, you'll be spending LOTS to get it perfect. i'm still not done paying for my bottom end stuff, because i'm a prick and absolutely have to keep my serial #'s correct with my motorset / chassis / registration / insurance / gauge cluster <3