8mm-06 would be fun, I had an 8x57 built a year ago, and had my Dad's old 98 rebarreled in 8mm Gibbs for him probably 20 years ago. Both a lot of fun, but these days, I'm thinking the 8x57 will do it all with a lot less fuss.
8mm-06 would be about as pain free as a wildcat gets, but don't overlook the x57. Load it to CIP spec and it doesn't give up much of anything to the '06.
