[GTJIM]

I reamed mine out to 11/32" straight through with a K-Line Chevy bronze valve guide reamer then turned up a new pin from the shank of a long 8mm Allen head capscrew (5/16" would do too!). Next, I fitted it with less than 0.001" clearance - nice thumb-press, sliding fit and held it in the upper hinge arm by a dob of MIG weld ... just like Opel did on the GT.
Drilled a 3/32" hole in through the centre hinge arm, with a small counter sink so that a needle nose grease gun tip can be used to grease it.

Just before you start - open the door and check where you can get a grease gun lined up with and mark the position to drill the greasing hole ... nearly had two holes in one of mine.

Good to go!