were these two aver mated from a factory? if not does aa or novak sell an adapter to mate these two?

i believe they both sell a clocking ring style adapter

yes, the both sell the adapters. you need to replace the main shaft to do it. you can also use a clocking ring to clock the 300 for more clearance. check this out for more info on the go2guy twister and the novak adapter http://www.pirate4x4.com/productreviews/scrambler/index.html