3 Point seat belt upper mount

[renegade6]

I need some ideas on where to mount the upper portion for my three point seat belts. I am thinking along the B pillar (#2 in picture) but, it isn't as well reinforced as newer cars the same issue goes for #1; it's not reinforced very well. I could put it on the lower point (#3) and it would be much easier to reinforce but, I'm a little concerned that it would be too low. I'm open for suggestions.

Thanks