That's a lotta offset with the scope setting so high. The rifle came out before flat tops were developed and were kind of intended to be paired with the Delta Elite 1911 in 10mm. In fact, I believe Colt offered them together in a package deal. These rifles commended a premium price at the the time and were Colt's flagship. It can be used as is, but there are far more practical ways to scope an AR today.
If you buy it, realize it will lose any value (if any) it has a collector's piece if you modify it. The Colt HBar of the era was a reliable, accurate rifle. If I recollect, this rifle has either the 1:9 or 1:7 rifling