JB weld is a brittle epoxy and will crack under vibs unless secured well. My suggestion: pull the Lbow clean contact surface with steel wool and wipe down all contact areas with lacquer thinner, acetone or alcohol. Secure Lbow with E6000 (I like the black) adhesive, I have used it on a lot of fixes on engines including my race outboards. Available at some arts and crafts stores and auto jobbers and others.
Put a thin skim coat of E6000 in hole contact surface and a thicker layer on the Lbow. Install and give it 24 -48 hrs to cure. The product is not silicone based and will not upset O2's and sticks really well to steel if surfaces prepped right. It is oil proof but not gasoline proof (if submerged in it). In your case the oil fumes will probably not harm it. Worth a try.
