JSpoo,
Just a few questions up front:
1. What do you want to do with your 243 when your barrel swap is completed?
2. Do you plan to carry it much with the Bull Barrel on it?
3. What is the farthest you plan to shoot your new rifle at?

You may have to swap out your Stock as well as the Barrel. Most Bull Barrels are quite large and they do not fit in many regular stocks without serious inletting. If you are planning on shooting heavier bullets for longer distances you will need a faster twist to stabalize them.

Jim Briggs
NSS