If you have to go to the trouble of mounting a Packard, then perhaps you should also consider a Sinar shutter.

Just as much hassle to mount, but you get the advantage of shutter speeds from 1/60th to 8 seconds.

So much more useful than a Packard in my opinion.

I guess you'd need to work out if you will continue using barrel lenses in future if you need to justify the price (circa $300), or whether you can get by with a Copal et al mounted lens for the same price.