Small block oiling issue

I have a 67 Valiant with the factory 273 still in it. It had the heads redone before I bought it. I decided to adjust the valves & noticed that the passenger side head doesn't seem to be getting much oil if any. I took both rocker assy's off & blew out the oil hole & it barely has any flow which concerns me. When I took the rocker assy's off,the DS shaft poured oil out & the PS haed a few drips. Where would you check the source? It's my daily driver