Prosport Gauges said:You can set it anywhere. i.e. 10 psi..
As far as the taper -that is what NPT is. I think the easiest thing for you is weld up that hole and start again or weld on a bung.
welding cast iron isnt a fun option.
id either use a helicoil on it, or get an adapter such as 1/4 npt to 1/8 npt.
also thought id mention, be sure it is 1/8 npt and not 1/8 pt.
npt is 27 pitch, and pt is 28 pitch.