Arrrrrrh not a problem, but you would have to get your STD barrell resleeved & bored out...... get a spare 49cc barrel bore it out & go that way... be about $380 for all the parts i would think
It should be OK - it's mainly inner rotor kits that do the crank mounted clutches in - and that's only because they are spinning at crank revs - so if the revs go up by heaps - the cast clutch spreads open because it can't hack the centrifugal force ! Due to the primary reduction gearing , mainshaft clutches only spin at around 1/3rd of crank revs .
If you end up having any problems , he could get you a H/D auto clutch cheap or you could go to manual clutch ! A friend of mine who used to build fast 50 Hondas , told me that he used to fit a type of thick band of rubber over the clutch to help them hold up to higher revs - but now you can buy a billet clutch cover that allows crank mounted clutches to handle super high revs and inner rotor kits . The rubber band also absorbed crankshaft harmonic vibrations .
All those jdmscooters cheat kits still have 49cc on the cylinder and look like top value for the $$$$ ! As I said - just be patient and give him a chance to send the parts - they'll get here ! I've bought off him a few times and I'm happy with him ! He takes only paypal so you are protected anyway if anything goes wrong .