a - get screw-in carrying handle mount. It does still allow you to use the iron sites as normal. Would this set optics too high above bore line?
b - get screw-in carry handle rail that is low and extends out over the barrel, putting sites co-witness with irons. Don't think a magnifier could be used with those, though?
c - cut off the carrying handle. Nah. Not really a fan of mangling the rifle.
d - get a flat top upper or whole new rifle / carbine like the rest of the cool kids. That gets kind of expensive and would be greedier than I could justify. Then I've spent a lot of money and still wouldn't have optics yet.

Though looking at the multigun/3gun thread pics I'd certainly stand out not having a flat top.
On a side note, how far out is an Aimpoint good for and how far out with say 2.5x/3x magnifier?