That's a fascinating build you've got going on there Harold. I've been following. It would be great if I can find that fork. I'm using motorcycle tires and rims so I need about 3.5" at the upper part of the fork. It seems like vintage bike forks are out of the question. Waiting for an answer from the guy you bought from Harold. In a mean time I found another guy building them:
I don't think they are quite as attractive (or authentic) in appearance without the tripple reinforced crown, but it looks like an option.
Motogaz, it looks like took apart a springer fork? I have a Monark fork but it's not wide enough and I wouldn't want to try to bend it.
I also played around trailer springs and have decided they are too thick. I may try some old snowmobile sprints as others have done. I'm really set on that curled under loop.