Hi there ,that kit is fine for conversion. Tamiya supply 2 type of props one scale and one to be used for motor's . As for prop shaft I would get down to your local model shop and get some brass rod and brass tube and then cut to the required length. For couplings use silicone fuel tube . For motors you have 2 choices . Get some small motors at a show or ebay or you can get a normal sized servo and use the motor in that . the p.c.b in the servo can be used as a speed controller there are threads on here on how to do that. 4.8v to 6v is normal best.
John