See if some of these links to past threads helps.

Adding lifter valley holes for camshaft oiling

Drilling additional holes for oiling and/or venting

Valley holes for aiding crankcase evacuation

Lorena, Texas (South of Waco)

Drilling the lifter bosses has been discussed at length on this site. You should be able to search it out. Our moderator Ted has done the mod and his comments are available back some. Personally, I would not do it. For one thing if done wrong the block can be ruined. The thrust plate mod is likely a good one, but proper cam end clearance may be more important.

Paul

I was reading in the Ford Y-block book from James Eickman about some modifications:

1. Drill and chamfer 1/4 inch hole  of the base of each lifter bore boss and then grinding grooves along the boss to increase oil contact.

2. Cutting slots on the thrust plate of the cam to increase lubrication.

Does anyone do these mods?  Do they work?

Appreciate input