Here's a Packard Shutter to use with the (there was a url link here which no longer exists) I just posted.
This is the No. 6 which is the good one with Instantaneous and if you take the pin or nail out of the hole, it stays open until you suck it shut with the bulb. I've got a page at my site for the Packard Uninitiated.
This one is working perfectly, and it even has the scarce contacts for Studio flash.
Lens board and lens shown NOT included. $85 + shipping.