for the cost of getting stock jugs punch and big bore sleeves added you can get after market jugs and sell those. how ever if your not looking at making a drag bike then this isnt your route to go...
first off theres no reason to punch those jugs to simply run a big bore piston. the amount of power your going to get vice the life span on those stock jugs isnt worth it.
stick with the closest bore size thats one them and get the mods you listed plus a 4mil stroker. just keep in mind there is not one mod at a time type thing whith this. with the motor comes a new clutch, and a longer swinger, with swinger comes longer chain, whe you get a new chain you dont want to run old sprokets... catch my drift?