Coronach, yes, shooting at golf balls at 200 is fun, but they are actually more like .75 moa in diameter. Regulation diameter is something like no less than 1.6".
Racinfan, I'm feeling for you. Putting an optic on a A2 isn't easy or the best way to go. I could see going with the mount that fits into the groove on the carry handle and then adding one of those cheek risers to the stock, if you have an A2, but it's less than I deal.
Personally, I'd swap the upper. You can get a blemished upper for around $60. The only problem is having someone to put it on. I'd do it for you, but I wouldn't let anyone that I don't know go monkeying around with my rifle.
What make of rifle do you have now? Is the Stag a worthwhile trade? You really need to pay attention to things like barrel twist and match that to the intended purpose of the rifle, although 1:9 is pretty much a commercial standard. If you had a flat top all you would really NEED is a good set of rings to mount the scope, again assuming that you have a full length stock.
Getting back to the original question. What are you going to be shooting at. A red dot does extend your range to a degree in sense that it's easier to shoot since you are only lining things up on two planes rather than three. The easiest thing to do, considering your upper would be to look into the C-More red dot with the integral handle mount. It allows a good co-witness and would require nothing more than turning a screw to install. I used to run a C-More years ago, before I went to Aimpoints, and they are very tough.
Something like this...
http://www.midwayusa.com/viewproduct/?productnumber=118105
I know that particular model has a huge dot, but others are available.