it would be very hard to convert and vertical shaft to a horizontal shaft to give you an idear of what you would have to do you would have to install a oil pump,put carby up so it can be filled with fuel,and change where tank is mounted,change where the oil top up is thats just a few problem you will come across.
C.MacMartin
if you have any other questions please contact me a masterc@xtra.co.nz