Was a pretty common wildcat with surplus German Mausers. Simply take a 30-06 reamer to a 8x57 and vola, 8-06. Was en easy way to use liberated and surplus rifles after the war. Quality Cartridge used to offers special run brass, but they say they will make a run with a big enough order. Not sure how many it takes to make a special run.
Too bad it's about impossible to find head stamped brass. It would really be a nice cartridge for Africa or anywhere else.
Regardless, I have an older gunsmith friend that says it is an excellent cartridge, and makes sense. The 8mm-06 outperforms the 8x57 Mauser by providing a 150 to 200 feet per second increase in muzzle velocity and 300 to 500 foot-pounds more muzzle energy. That's a noticeable difference basically a twin to the 8x64mm Brenneke.
I tend to avoid wildcats, but it has always been interesting to me.