Why not install a 4 inch Venturi on the side or the belly of the
aircraft ( 50 bucks aircraft spruce) then route to a selector valve
then you could switch between engine pump or venturi. This will drive
BOTH AI and the DG.

Or you could install the venturi to drive a back up CHEAP ( older type;
black face) Gyro Horiz. I am sure an instrument shop will sell you one
at a good price as every one wants a color faced type.

Now what about BACK UP electrical power thats CHEAP and portable!


I use one in my Airplane it provides 5 hours of FULL Avionics power !
It cost LESS than 30 bucks to make and all parts are from WAL - MART!


Hint: GARDEN TRACTOR