cam cover vent hole size

I'm wanting to run SS tubing for oil lines & for the life of me I can't find a fitting to adapt the 3/8-24 hole to an inverted male flare for 3/8 tube. Anybody successfully chase the hole to 1/8 NPT? I can find the fitting to do the job then. I do plan on leaving a short length of hose at the ends up on the oil tank but want the lines secured on the engine side.
Any other ideas are more than welcomed as well!

Thanks,
-DH