I did not see this when first posted but I might not have had a good answer anyway. Do you really have a check valve with 10-32 on each end? Not seen that, so my best thought would have been to change methods. Probably not what you wanted anyway?
I use the Fabco NV-55 on a couple tanks and have found it works for me to buy a dozen or so of the plastic 10-32 to barb fittings. I then use common airline to tie the various parts together. With the flex of the tubing, I have no trouble with breaking the small fittings. I find the 10-32 fittings are used several places that we would not normally shop like medical/dental equipment, RC car fuel lines, etc. But my best buy has been from Arkansas Plastics or US plastics if you are ordering other things at the time.
Good luck to you.