What types of wildcat chamberings are out there for use in a short action. And how would they rival the .308 Win.

what do you want to achieve?

if you want larger then something based on the 284 would be good, if you wanted even bigger get something based on the WSM/SAUM.

the 6.5-284 is fairly popular due to its recent success in long range benchrest and F-class. and im sure someones has done it from 22-338 with the 284 case.

basically the 284 and WSMs will give you higher velocity, higher recoil, use more powder. but you get flatter shooting and more energy for stacking more powder in there