HA, I'm doing what you just did. DB17 with a 1717. I won't be using that motor mount and I did not buy the heli version.
I will be building/making my a motor mount out of some 1/4" stainless steel square tube I found at my job. Just have to cut it down to size, drill out the motor mount side, and tap the bottom for the stock mounting screws.
The piece I'm cutting out of is around 4" x 6" x 36". I'll be cutting a small L out of it.
This is what the metal I will be using looks like (similar).
