Merlin: You may want to consider a SQ D "Mini Power Zone' factory assembled unit Primary CB/Sec CB/ & 120-240 volt branch breakers all in one 3R setup, right out of the box.
MPZ5S40F is a 5 kva; 10 single pole spaces for QO CB's
May be considered pricey....but ya get what ya pay for, and it's all ready to go.
