ok well now youre not making any sense. if you have to run a 1mm spacer plate anyway then why not run a thicker one to accommodate the 10mm crank? thats just stupid not to. crank prices are the same as well as trenching. with either motor you really need to be running at least 39mm carbs, straight cut gears, lockup, big air filters and a good solid clutch. it doesnt make any sense to build a 7mm at this point. there have been many guys that built 10mm out of stock cylinders than ran very well.. honestly, i dont think you have any clue as to what youre doing is you think you cant build a 10mm. the spacer plate will raise the cylinders back up to get your port timing back to where you need it.