Hi guys, original poster here with an update. Heidi at Ost2rad was great in working through the problem I had with the header and has issued a refund. Unfortunately this is the only down pipe they have so no dice there. It appears that our very own Guesi has the correct down pipe so I would recommend his outfit.
In the mean time I learned a lot and found this board/forum to be one of the best that I have belonged to. Thanks guys. (Gratuitous MZ photo)