Two Sons Plumbing just helped us install a boiler for our radiant heater and they were awesome and about half the cost of all the other bids. Not sure if you issues but they might be helpful.
Try Energy Works. They did a great job replacing our radiant/tankless system with a boiler/indirect tank a few years ago. The tech I worked with (Kaleb) was incredibly knowledgable about how those systems worked. Couldn't be happier. You couldn't pay me enough to go back to tankless...