[blykins]

I think I may go this route:

In the picture below, at the end of the arrow is a straight portion of frame directly under the trunk. (This is a picture from ravedemon.)

I'm going to drill there on each side. That should be pretty well inline with the "y" part of the shoulder harness. I'll drill through the whole thing and just run a bolt down through it.

My body is on the car, so I guess I'll drill up from the bottom. I don't have a right angle drill motor, so that's my only choice.

I wouldn't think it would weaken the frame at that point. SV drills through the main frame rails to attach the cowl hoop....