there are many different 240 kits. there is vitos, la sleeve co. (which i reccomend), trinity racing used to make a 265 big bore kit... basically a stock top end is 66mm. a .040 over will make you a 67mm piston. a 240 kit will give you a 72mm piston. and as for porting there many different people for that as well. you can click the link in noobers sig, click the link in my sig, theres angus kennedy of kennedy powersports... each partial to their own