Model A and Model B Valve Tappets--Lube Holes?

[Bud]

I have noticed that the original tappets for the Model A and Model B are drilled with a lube hole in the center of the tappet facing the cam and I presume this hole connects with the lateral hole in the side of the tappet "shank". Can anyone shed light on the size of these holes, depth and location? Are they indeed for lubrication?
When I had my 8N tractor rebuilt in the mid 1980's the shop doing the work drilled the side of the tappet bosses in the block to lubricate the tappets. I have not seen this done on Model A's or B's but I think it would be a good idea if the current tappets do not have the original lube holes provided by Ford.