Some of the best black Purebred Maine's are fairly intensely linebred to Cunia. If you think your Cunia cow goes back to a productive type Angus cow you could breed her to a homozygous black-solid purebred or percentage Maine bull . Either way, heifer or bull would have potential value and something you could paper. O'hara Land and Cattle, Green Valley Ranch, K&A would be a few outfits to start inquiring. A Shorthorn bull might also be another choice which could yeild a red or a black calf (either color is a winner), that could be registered.
I also really like the bull Ready 2 Rumble from Lautner's line-up and know he is not yet proven in the color department, but think his pedigree is really interesting. He is a TH carrier but even if you don't get the positive status (For the real world) you might get something special. His pedigree should really play off of Cunia, IMO. He might be the risk taker here but that is how I like to play around with mating decisions. The Thriller bull is also something that seems to work well and has produced some interesting Maine show cattle as well as some steers.
What I would try an avoid would be the white socks from the Maine genetics. I'm not a big fan of them.
Just some ideas to confuse you.