Most people say buy good glass...you will never regret it. But in your case I would ask myself a few questions before dropping $1000+ on a spotting scope.
Is this going to be a once in a lifetime hunt? Will you likely hunt somewhere that you can utilize a spotting scope ever again? How much are you willing to spend? Do you really need a spotting scope for this hunt?
If you are going to be hunting strictly private land, there will be roads pretty much everywhere. So there is a good chance you will be able to get a closer look from the pickup, in most cases a decent set of binos will be enough. Now if there is a chance that you will be hunting down in the breaks then definitely get a spotting scope.
Talk to the landowner if at all possible. That will be the best source of info. If he has done any hunting to speak of then he should be able to answer most of your questions.
I have been hunting the prairie of montana for 20+ years and I don't consider my spotting scope as mandatory equipment. I have a 82mm Nikon fieldscope ED and I do use it often, but if I didn't have it, I would still be out there.
If you do decide that you need a scope my suggestion would be to get a spotting scope with a variable power eye piece. Something in the neighborhood or 18X on the low end a 50X on the high end. I would go with at least a 60mm objective and don't even consider anything under 50mm. The high dollar scopes do have better glass and are more pleasant to use, but the lower end scopes are better than nothing.
The only taxidermist that I could find in the Glasgow phone book was Kent Morehouse. If my memory serves me right he only mounts fish (don't quote me on that), so that won't help you much. I know there was a taxidermist in Glasgow that worked on big game, but cannot remember his name. My advice would be to go to D&G (local sporting goods store) and ask one of the guys at the gun counter. They can point you in the right direction. Besides it will give you a chance to look at the mounts they have. That should get your blood pumping.
Good luck and don't forget to have fun.