I bought a Yildiz 410 SxS recently for just such a project. It is quite a nice little gun with a single trigger with mechanical operation for the second barrel. It has a double underbite action but does not have a 3rd bite. I have done a few calculations and all seems fine. I am doing mine in 22K Hornet as I will be able to get normal ballistics at lower pressure. I plan on working up a low pressure load in my bolt action K Hornet with a 35Gr Hornafy V Max at about 2700fps and regulating the rifle for that. I will be building a monobloc rather than chopping the existing barrels so I will have the best of both worlds. Good luck with your project!