Darkhorse, thanks very much for the clarification about your magic trigger. I think for this first build I will call Stan Hollenbaugh as another poster suggested and learn more about his single set double action trigger. If it fits, and if it's great, it will be much less expensive than having to buy another lock to replace the first one I would undoubtedly mangle in my search for the excellent crisp, light trigger!
I look forward to seeing images of your Isaac Hains rifles, if you get inspired to gather and post them sometime.
Thanks again.