Don't know for sure about these engines, but most all others that I've messed around with have the con rod bushing pressed into the rod. If that is the case here, you may need to replace the entire rod, or have a machine shop make you a bushing and press it in, and then hone it to fit your piston pin.
If you can't locate one you could measure it, and get one from mcmaster carr. Then you can have a machine shop press out the old one, drill the oil hole(and chamfer the edges) in new one, ream it to fit your wrist pin diameter and press it in. Mcmaster has tons of brass bushings and bearings, you just need to know the dimensions.