Replacing fuel cut-off valve with non-a/c part???

Folks -
I have a '46 Taylorcraft with a leaking fuel cut-off valve. I suspect
the valve stem packing is causing the problem. As this is the third
time I"ve had to address a seep with this original valve, I'd like to
replace it. I believe a ball type valve from the local hardware store
would do the trick, as it has no parts that would be harmed by
gasoline. It appears to be all brass with teflon bearings.

A look at the FAR indicates replacing the valve is not a major thing
and a 337 is not require; however, the proposed valve is not certified
for use in an a/c.

I plan on talking with the local FSDO, but until then, can someone
provide any insight into what I'm going to have to do? Thanks, Mike