You are going waaay back with the mecatwin. I only found out about them when I found two 3 pin connectors on mt CT-1/2 pack. I think the twin was usually used for a fill to the main pack.

Bite the bullet, and bring another old pack and head flash back to life. If you are looking for more omph, then battery powered this is going to be challenging.

Old Norman packs can live almost forever (not their nicad packs and chargers thoughh - swap AGM lead acid or NiMh or Li-ion in and charge it accordingly.
They have the ability to run bare bulb, mount to a speed ring gracefully for a soft box, or use there usual reflector.
They are not really auto flash, but with multiple heads autoflash is usally not viable.

I have an old blue colured 200B. I believe there were 400 and 800 w/s battery powered packs as well.