KOOTANS 4pcs Brass Hose Barb Fittings 1/4" Hose Barb to 1/8 NPT Male Thread Air Hose Fittings Brass Quick Coupler Air M Type Adapter Connector Fitting

Tap it using a 1/8 NPT tap, compare hole size to tap, and use a 1/8 barb brass fitting, you might have to go up to the next size which is 1/4 NPT. Barb fitting should screw right in, use 3 wraps of teflon tape on threads to seal. https://www.amazon.com/KOOTANS-Brass-Coupler-Fitting-Quick-Connect/dp/B07P962KXQ/ref=sr_1_2?crid=YDSECGY8FICM&dib=eyJ2IjoiMSJ9.45D2aYJgLkiidny3OId9iBU8RvS4vpl1otL2KJ-if0N6avLZiNZ7GDQd_PB3Pk8JvdYGwttCLD5lRVZoC2C3nWNLWkaDmTHlWa2zzjiCdOORGOS8jgD3oL8NKMl5afzSw5KXWLk4b0WU4xh9Gir6PMV3FCs1DjvLsVbzPjRsXG87MsBJkhvvAKBSVsfjrTFl8SZ4aeLld9GAdIhBalIfDljX9Eh6HLebK7Vnvg1V9MY.XFoGCZ-3eiRPF1lW_m0aUDEyNBy9DeXUTxx_F7huxGE&dib_tag=se&keywords=1%2F8%2Bnpt%2Bhose%2Bbarb&qid=1781214458&sprefix=1%2F8%2Bnpt%2Bhose%2B%2Caps%2C238&sr=8-2&th=1