well if you realy want to have your grandkids to beable to drive it you might want to put a geo metro motor in it...

....sorry.... gas is $2.35 a gal here
i would keep the stock motor and rebuild iit....20-.40 over.....find a five speed from an izuzu pup(takes some work) and do the elect ignition conversion.
after that there's a performance weber carb(dgev 32/36)that works well,and a header with a 2"exaust. there's a few other things you can do like a v-6/v-8 swap but if you want to afford gas in 10 years.......
good luck and welcome to the club.........