I guess I didn't realize it needed an answer.

In my case, I didn't have the recesses in the outside of the runners filled in completely in the area directly adjacent to the bolts.

I did a little clearancing around the bolt area and test fit the intake and made sure I could get all the bolts in prior to doing any porting in the runners, and just didn't open them up fully at the bottom where it started to feel thin.
I still ended up barely dimpling one of them...... And I smeared a little JB weld on the outside to seal any possible leak.

I used header bolts with the heads ground a little shorter in those 4 holes.

This all happened quite a long while ago, but as I recall the intake mod was worth over a tenth on a friends S/G car.