After reading some more I think installing a new coil in your old case would be the way to go if you're going for looks.
No such thing as a coil case. The electrolock cap fits on the top side of the coil itself. The OEM coil (in '38 anyway) had the fastening mechanism built into the coil. Replacement coils came with a bracket that screwed onto the top of the coil for the electrolock cap to fasten to. I spent a lot of time on ebay buying aftermarket electrolock coils when they became available and were affordable. I have three or four spares in my archive. The best advise I can give the OP is to watch ebay at least once a week and start hitting swap meets. No one I'm aware of repops those coils. As noted above those who have some in stock are really proud of them. Short term you can make any 6v coil work but it won't look right to those who know what they are supposed to look like.
All you have is the strap that holds the coil to the side cover. How to remove the cap and showing the replacement coil bracket. BTW I've not found anyone selling the special tool for removing the cap. It takes a very thin but stiff blade to fit between the coil & cap. You can save yourself some future headaches by using a dremel tool and grinding the locking tab off of the inside of the electrolock cap so that any time in the future that you need to remove it all you do is twist it off, you don't have to mess with trying to get to the locking tab. I destroyed my OEM coil trying to get the cap off.
