I also asked the guys at Peterborough Auto because I need to hear the voices of experience to guide me.
All three of them (with at least 2 of them owning vintage rides) suggest drilling out the slingshot holes and using my original bolts that held the generator on. I thought of that. I just didn't want to do that and find out there were wiser options.
Thank you Pugsy and Jarvis. I may be overly cautious but I am trying to do things correctly.
To be clear, the block takes fine thread bolts and the slingshot mount has course threads. Otherwise, it fits perfectly. Thanks guys.
My apologies - I was unclear. It is the 2 holes at the base of the slingshot I was unsure about, not the 2 holes at the top of the mount that hold the alternator. The 2 holes at the base line up perfectly with the block holes so I will drill out the slingshot lower mounting holes.
Thank you everyone for taking the time to assist an idiot. I may be stupid but I'm learning.