I'd keep the MAK 90
I don't see many MAK 90's in .223 I would think that it would add to the value as well.
I have both a MAK 90 in 7.62 X 39 and a Mini 14 in .223. The mini has been problamatic from day one. I was low on cash and my father purchased it from me. Never really missed it. Then when me retired and moved, he gave it back to me. Still don't have much desire to take it out as I have other rifles that I enjoy shooting better.
My gunsmith hates Mini 14's. He says he fixed tons of them over the years. The MAK 90 has never given me any issues over the years.
"Get rid of that chrome plated sissy pistol and get yourself a GLOCK"