Since there seems to be a discussion here from people who have never done it, I will start by saying that it is worth it. I have been riding mine now for about 18 months. It is a great swap for anyone that can't run wide open all the time everywhere they go. I had actually forgotten just how shitty the Banshee motor is until I bought a stocker the other day.
While you can't use RZ cases with Banshee jugs, you can use Banshee cases with RZ jugs. The only downfall I have found with using a complete RZ motor is the gear ratios make it just seem slower. I have riiden a complete swap and mine which is RZ jugs on a Banshee bottom end.
To do what I did is pretty simple, it's the wiring that sucks. The RZ wiring harness get's hacked down to about 1/3 of the original wires.
I have also found that some people can't set the powervalves up either. The valves are set to move a set distance, but you can set the start and stop incorrectly. That is almost always the culprit of one that just doesn't run the way it should. When mine was ported the builder actually drilled a hole in my cylinders and powervalves so all I had to do was stick a toothpick through there and adjust the cables to hold them at that point.
I like the motor so much I bought another top end to turn into a stroker. I do believe it was a great swap, it gives the Bansheethe motor it should have had from the Factory. The only part that sucks about putting the complete motor in is the gear ratios, but that turd can be shined with changing front are rear cogs.
Good luck, if you have any questions, just PM me.
broke