Colt AR-15 HBAR

I have a Colt HBAR (Pre ban) that I bought sometime in the late 80's- early 90's, before they started putting removable carry handles on them. I have a shorter DD AR in M-4 type configuration, but would like to have a longer barreled AR without a carry handle to put some nice optics on. I have a scope mount for the handle, but that puts the scope way above the bore. I was thinking about reconfiguring it, but if I put a new upper/barrel on it, I could almost buy a new one. I see new upper parts w/o the barrel advertised for less than $100, but I'm not 100% they are compatible. The rifle, as it is, is very accurate with iron sights. SO I'm really just kicking ideas around... if it were you, would you reconfigure this in such a way you could put it back to original, or would you just put it in the back of the safe and get a new one? I'm not sure what the value on this rifle is, it has fluctuated so much over it's life, depending on who was banning what. I think I paid $600 for it, saw them going for $2500 during the ban, and now I think they are mostly going for around a grand. If it didn't shoot so well, I would just leave it alone, but I keep thinking that with the right glass, the thing would be a blast.

You can buy a DPMS flattop right now for 399. I bought 2 on black friday and they shoot great. That Colt is too valuable to customize.

Check out Palmetto State Armory. I have some uppers from there that shoot pretty well.

Likewise, I would buy a flattop upper so I could still have the complete Colt if I wanted.