Monogram 1:48 F-106 Delta Dart

I may try to cut cardboard (from the box) in the shape of the doors and enlarge as necessary to fit.  I did this once an A-7 nose gear cover when the original would not fit in the gear up position

I remember building thatkit when I was a teenager. You might try to see if you can use sheet styrene and custom cut the pieces you need to make the closed doors. Then you only have to worry about the curved portions of the doors. 

I have.  The parts do not line up very well, I remember having to use a bit of pitty to get them to look even close.  Some of that is certainly operator error, but some of it was the basic fit.  They are just not designed to fit nicely closed.

Good luck, and please share your success.

John