http://aperturesnmore.com/This guy can make you about any aperture you want for about $12
Mounting screws are not a hard problem to solve either. Our friend Lightfoot can probably hook you up. If not plenty of other sources.
Jaaack's offer is very reasonable. He's trying to help you out
I agree. Thanks, for the input.
I still can't PM so hopefully 99guy sees this plea for help. I tried to contact "aperturesnmore" but after registering I still couldn't send the contact/query form with my questions. Is this company still in business? To your knowledge. (I was questioning the 1/2" vs. 5/8" option for the Lyman 57SB. Is this the diameter of the knurled part of the aperture?)
I didn't see a phone number for this company on their website.
Update. I did find the company on Ebay that seems active so I'll try there. The website is broke.