Hi,
From experience of building several MMM tugs (Norton Cross, Eldergarth, gribbin head, Portgarth) I would give the fittings a wide berth and go for the hull and plan only then source your own building materials and fittings elsewhere. The fittings that came with the MMM tugs I have built, to be diplomatic, left a lot to be desired but you never know they might be of better quality now. For top quality hulls and plans I would recommend you contact Steve at "Scale Hobbies, Skelmersdale" he does a nice range of tugs. He no longer has a shop but still supplies from his home address, his hulls are built to order so haven't been sitting on a shelf for months. I recently asked Steve to make me one of his Oakgarth hulls which I collected last month and the quality is excellent, perfectly symmetrical and all the bulwarks straight and nicely trimmed, the price was also very competitive. Hope this helps, good luck.
Regards, Pete.