Over the weekend I purchased an adjustable proportioning valve that accepts both front and rear lines. I had to do some replumbing of the lines and fab a homemade bracket but got it in. So far no leaks.
BTW - If anyone needs to run double flares on brake lines I would highly recommend the Titan tool. I have no financial incentive, no freebies etc but the tool worked way better than those typical flare kits. If anyone wants me to post a pic of it let me know. Nice to use a tool that works nicely.