Bast*** "Machine Shops/Engine Rebuilders" !

The bolt with hole gets oil from the very front corner of the valley, not pressurized, about 3/8ish of an inch below the 1 inch front valleys drain holes.
There's tons of oil in the valley returning from the heads and lifters .
I think the whole bolt with hole etc is related to type of chain, (link/roller) gear type (plastic), that was installed at the factory, - replacement chain/gear type likely changed thru the years, - fasteners didn't . .jmo