jets, carb, single?

Hi Guys,

I have a 1980 KZ440B I've been working on for a month now. It sat untouched in the original owner's garage since the early 1990's. I rebuilt the carbs, cleaned everythig up and got in running in stock form before all the changes.
After I started modifying it, I started reading about all the issues that go along with changing the intake and exhaust.

The pods went on first and it ran ok so I bumped the main jet up to a 72 and left the secondary (the bike is almost strictly a commuter across town so getting it above 4k wasn't likely). It ran very well with just the pods and stock exhaust but of course I wanted it to be louder than a vespa so I put a shorty on the stock pipes and also put 100 secondary mains in it as well. Now it runs like crap. It starts fine and idles but there's a huge hesitation getting it above idle and then hangs at a higher rpm after letting go. Adjusting the mixture screws doesn't seem to change much. I've checked the float level and they seem to be correct.

I butterfly'd the shorty with a washer to see if that would help at all but that doesn't seem to do much either. I would consider welding the old pipe back on but there are big chunks of the insides (catalytic?) bouncing around inside when you shake it, so I don't really want to do that. I'm not exceptional with tuning carbs beyond rebuilding and changing out jets.

My other option is another set of carbs or a single carb, which I would rather do. I have made the parts for the manifold, and wouldn't take much to make it but I need some input on which carb. I figured I would use a Mikuni VM, but which size should I go with? 34, 36, 38?

The bike's current form


Manifold material

off topic but awesome looking bike. Did you make the seat yourself?

Thanks. Yes, I did the seat and all the work myself. I have a small shop where I do fab work. Here are a few more pictures.