I have an old probably late 70s early 80s with the original barrel that was cut down to 18" by the first owner. I was thinking the same as you. But the 2 3/4 chamber is not a big deal and the 2 3/4 buck, reduced recoil and field loads are easy to find. Not to mention the all metal construction and this thing is a tank. I got it Cerra coated in green and left the stock and forend the natural wood. It looks nice but I need to redo the wood and seal it with some poly. For $200 its a nice deal with a lot of potential. Instead of cutting it down you could get a 18" barrel from a few different companies.
GLOCK Certified Armorer