The sight on the right looks like an ArmaLite designed for a low gas block rail. It or one like it should solve your problem. There are flip ups of that height but again make sure the height is right.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
You'll remember the quality of a gun long after you forget how much you paid for it.
US Army 1966-69, VFW Life Member, Retired Geek