bjuice

the 400 in the 69 camaro we have has bosses where the drivers side low mount altenator brackets holes normally go...My question ('s) for you guys is this.
#1- how much block material is behind these bosses for drilling and tapping ?

2- what would be some ideas on drilling and tapping this bosses..without the obvious ( tearing motor down etc...).....

i do realize this is not the perfect senerio for the hand drill etc....

i was thinking maybe some of you guys have done this job while engine is still in car and make yourself a makshift jig or something.

thanks Brian