I seem to recall that the Webra .61, YS .60, CMB 60 and a few others had the same exhaust mounting for the RE engines. The Webra 80 fan engine was base off of the Speed .61 engine.
That might be of some help.
Also, check out Allen over at Weston - in the UK.
He may have exactly what you need for your DF exhaust system, and he is a whole-hearted webra distributor. No doubt he can set you up with the pipe and header combination.
http://www.westonuk.co.uk/index_160.htm
Bob