Ok here's how to bolt an Old A and have a decent headtube angle. Trust me i ride Old A's..
What you need:
7/16 x 2 1/2 in. bolt
1 x 7/16 nylon lock nut + 2 washers (7/16)
5/16 x 2 1/2 in. bolt
1 x 5/16 nylon lock nut + 2 washers (5/16)
And a 5/16 x 2 1/2 in. bolt and a nut for the bottom hole but i'm assuming you know that.
Ok so here's what you gotta do..
1. Cut off the plates in front, it's easy just take a hack saw and press it up against the side of the foldy then start sawing. Once you sawed through, take pliers and just bend the plate and snap it off.
2. Bolt the headtube in with the bottom bolt, and no bolts in the slot or behind the headtube.
3. Take a drill and drill out behind the headtube, just make that square piece that sticks out and make it rounded. You will see it, it prevents the bolt from being farther back, just round it out.
4. Now that it's rounded, stick the 7/16 bolt in there, now push the headtube back up against the bolt.
5. Tighten the 7/16 bolt down. And now try and put the 5/16 bolt in the slot, if it doesn't fit then take a drill bit and drill it out.
6. Put the 5/16 bolt in the slot now, and tighten everything.