I think it should be crossed with sargintianum. It would be interesting to see how much red you can get into it with out besseae. Sarginteanum would increase the size of the plant, but I still think it would be an interesting cross because of the red in sarginteanum.
Popowii should give some interesting color.
Usually I like compact crosses, so my next choice would be fisherii. Or if you have a clone of pearcii with a lot of red give it a try.