You could try crossing them yourself and harvesting the seeds to see what you get.
Other than that, if you want to try something with a lot of meat that makes a good sauce but has good flavor uncooked, you can try any number of paste or some other tomatoes. Jersey Devil, San Marzano, Amish Paste among many others. For non-paste tomatoes, kellogg's breakfast was very meaty (good sauce) and had good fresh flavor for me. Bi-color (yellow/red) tomatoes like hillbilly potato leaf, gold medal, and big rainbow might be good to try.
My true black brandywine tomatoes were meaty (again, good sauce potential) and had good flavor too. Carbon maybe, they're smaller but meaty as well.
No one can really say for sure about the flavor, some tomatoes taste like water balloons filled with well water in some climates but may be the best tomato you've ever eaten in another climate or different growing year. The only thing to go off of really is whether they're meaty or juicy, the juicy tomatoes are generally better for salads and sandwiches and stuff, but will take a ton of them to make sauce.
