I finally got a mount design that I'm happy with.  All the numbers seem to be in order.  So then I grab my Spruce catalogue to investigate mount bushings.  Two pages of bushings and not a single radius listed anywhere.  It's my understanding the the conical mounts do a better job of isolating vibration, and I can machine sockets for them.  I just need to know what size.  Does anyone have one or two that they can lay a set of calipers on?