Installing Shadin Digiflo in Piper Apache (Need STC or '337)

Hi All,

I've acquired a Shadin Digiflo (twin) and would like to install it in my
1955 Piper Apache. My mechanic called my local FSDO, who mentioned that
without an STC, the best way to proceed would be to provide the FSDO with a
'337 that was approved for another installation in the same make and model
for review. Pending a satisfactory review by the FSDO, my mechanic would
install in the same manner, generate a new '337, and we'd be in good shape
to have the installation approved.

So, has anyone done this? Incidentally, my A/C has O320-A3B's in it.

Thoughts?

Thanks,
Dan