Distributor install issues lyb

[B-ster]

Ok. So I removed the plug in the outside of the block so I can access the oil galley plug that feeds oil to the distributor gear. I tried tightening it so the gear will clear it but it was bottomed out so I removed it. I talked to my mechanic and he told me that if it's too far out that I can grind the back of it down making it go further into the block giving me clearance to install the distributor. I ground about 1/4" off the back, leaving 1/4" to screw in. That plug now won't go in but two turns and stops abruptly. I tried using a tap but it goes too far in before starting to clean up the threads and hits the lifter. So now I have a 1/4" plug still sticking out interfering with the distributor gear. i don't know if this was the original plug or not, nor do I know if maybe it's supposed to be tapered so it'll go in further. I could bring off the front of it, leaving enough of the Allen head to still screw it in and use thread lock. But it just seems like this isn't the right plug . It does have a hole in it with a star pattern so it looks right
If anyone knows the dimensions of the oil galley plug for a lyb 54, and what I need to do to get this problem resolved, please let me know. it's been one thing after another. Thanks