Rocker shaft oil passage?

'67 barracuda slant, true barn find(40 yrs off the road), got it running, no oil to rockers. Installed mechanical gauge 40-45 psi idle. Everything I find says oil passage rear shaft bolt with "special bolt". Removed each shaft bolt none are special(no banjo style bolts or relief cuts). Used a welding wire and cant find any oil passage through any rocker stand. Also used 10' phillips screw driver and a hammer at rear rocker stand and can't get past 2 3/4' deep. Rockers are adjustable, seems it is a little over 100k miles, original and never been apart(based on old caked on grease solidified sludge). Rocker shaft seemed to be over half full of the old oil but has run 15-20 minutes total time getting it to run w/o seeing any oil to rockers. I want to find the actual passage and make sure it's open but find none. Carb & water pump replaced. tune up, radiator repaired want to test drive it but a lilttle stumped on not finding that oil passage in the rear most rocker pedestal. Is there something different about this early of a slant (referring to the oil passage). Service manual only says be sure to install long retainer in center position only and install long bolt rear of the the engine. It does show an image of the head inverted pointing out the oil passage which looks really small, maybe too small for my phillips to pass? Anybody know just how big this passage is? Thoughts/comments? Should we just soak the top end down in oil and try driving it in the driveway a bit see what happens or continue trying to get an oil passage opened up? Thanks...