Stan, with all due respect you are going about this the wrong way. You should first determine what load you need in your shop (a lot of guys get along fine with 60 amps) and make sure you can pull the required amperage off of your current panel (this would make the panel in your shop a "subpanel"). Once you have decided on your amperage and you know how far it has to run then go look up the voltage drop tables and find out what wire size you need. If that happens to be 8AWG then fine, use it. Otherwise just buy the wire you need. The expense will be trivial compared to the effort it will be to get power to your shop, and to the benefit (and value) you will get. And, it will be to code! Have you considered what would happen if there were a fire in your shop and your insurance company found a bunch of illegal wiring? Think one of today's insurance companies might try to weasel out of paying? I sure do! Do it right, do it once. Even if you can't use the 8AWG for pulling your subpanel, you may well be able to use it inside your shop when you wire all your outlets, etc.
Good on you for asking first!
GWE