hey mate, if your not planning a 4age conversion i would think about a k-motor. 5k/7k
im sure you aware of the conversion costs with a 4a conversion and the amount of parts you need. tailshaft, box engine and cross members, pedal box/hydro clutch system, modded fuel lines, radiator, thats before box and motor aye..
rollaclub is your best bet with all k-series stuff, just so you know..
5k= 1.5 moderately priced and fairly easy to find good on fuel
7k= 1.8 harder to find and more expensive