Basically it will be hard to find a decent builder. Most have retired, the young ones are are West building homes for Californians moving out of Cali.
Call Bensonwood out of Walpole, NH craftsmen and NH building products. They also have excellent project managers, even used your plans! That will be an excellent start! Some of your neighbors used Bensonwood
https://bensonwood.com/
New condensing boilers and on demand heaters are far more efficient and make looking into gas worth your while. They work well with the mini-split system for year round comfort. I know of one Bensonwood owner in Tuftonboro who did just that, I believe 5,000 sq foot, and is extremely satisfied. Cost less to heat/cool than my 1,500 sick built!