Finally decided to install a vapor return line and found the Andair check valve frequently used was horrendously priced.
Summit racing has a part that I decided to use instead. It is an all brass fuel system check valve with 1/4" NPT in and out. Photos attached W/part number. Delphi brands this and makes a whole lot of fuel system parts for auto and particularly racing use.
The check valve has no internal rubber parts and is all brass with a metal spring internally. The breakout pressure of the unit is approximately 1/2 PSI according to my pressure gauge so well within what is needed for the Rotax vapor line.
Price??? I paid $14.99 plus shipping from Summit.