Adding factory front shoulder belts in an early '68.

[challenger70]

I have an early production '68 and would like to add the shoulder belts in the front.  Where can I get a factory or close to factory mounting plate for the shoulder belt bolt?  Also do any of the other shoulder belt accessories require welding or drilling in the roof?  I have all the parts, I am just not sure how the clips and what not that hold the belt up in the headliner when your not using it work.