I looked at that sears combo gauge, and it only reads up to 10 psi.
They do have one for $40, but you would have to rig up a non-schrader
ended hose to it as well.

As far as the hardware store route, I wasn't sure if you needed some
sort of special gauge construction because you are dealing with
gasoline.

>Sears sells a nice combo vac/pressure gauge for $19.95 folks
>
>John
>Aircooled.Net Inc.