personaly i'd have just bought a used one on the stock bore that needed bored and rebuilt it when i had the extra cash. having a spare is great. i blew up my 04 a couple weeks ago an hour into an all day ride. a couple miles from home. me and a buddy loaded it up took it home threw the fresh spare on and were back 3hrs into the ride and met up with the guys and had half a day of riding left. with one cyl your down untill the machine shop has time to fit you into schedual and you can get a new piston and rings shipped to you.
i keep 2 spares ready to go even tho i've only blown up one blaster due to previous owner being cheap and only replacing rings when the cyl and piston were screwed.