If I remember correctly, the Direct Connection oil galley tube kit for a small block didn't say anything about holes for added oiling. Just peening the tube in each lifter bore on one side. Apparently with solid lifters, there is enough "splash" to provide enough lube. (I did it once - never again!)

Cam/lifter lubrication would be my biggest concern. But a little bit more through a small lube hole couldn't hurt with a flat tappet.