[Ronnieroadster]

Originally Posted by my2nd40

Some folks grind down the top of the lifter bore to aid in getting a wrench on the lifter bolt to make the adjustment. How much is too much to grind off. I've seen some pictures of engines in some books that the lifter bore looked to be ground down a 1/4" or even more. Won't that affect how the lifter might ride in the bore?

To answer your question the 1/4 inch example may sound excessive causing a loss of lifter stability but it really has no ill effect. There's almost no side loading of the flathead Ford lifter.
As an example of how the lifter bore design is more than adequate for the example above. There's a far more extreme lifter application used on the flathead when you put a set of ARDUN overhead valve heads on the flathead block. The liters required for the ARDUN conversion as close to twice the length of the flathead lifter. This additional length is required so the push rod can pass threw the original guide holes to actuate the rockers. This taller lifter increase side loading substantially due to this push rod angle location.
My experience after many thousands of miles with this additional lifter side loading has shown no additional lifter bore wear. This is of course an extreme example of possible lifter bore wear but as I wrote the bores handles all of it perfectly.
Ronnieroadster