I don't know if you want to or can pull the engine, but when I had a leak in my engine I pulled it and brought it down to Cal Dyno in Redwood City. I can't remember the owner's name but the's right off Broadway in the backshop of Elgin's Cams. He's very reasonable and when you have the engine out, you can see most everything. I also used a flourescent dye and turned the lights off in the dyno room. My leak was a brand new cracked
oil pan from the engine builder. Good luck.