New with GT550

Hi everyone

Just joined this forum because I've acquired a GT550 (this is a UK model also known as a Z550 G1) project (early 80s model).

Wondering about quite a lot of stuff... The difference between the Zephyr engined GT550 and this one, for example, and any similarities or differences with other 550 Kawasakis from this period. This project has been left standing and hasn't started (until now) for about 5 years. I got it started with a carb clean, fresh oil, oil filter and plugs.
I've bought myself a Haynes manual and have been reading it. When I've got the running sorted, it will need other things taking care of, such as the shaft drive oil, tachometer, etc.

The bike has got several issues, not least of which is that it simply doesn't idle. The engine seems to be fine. It will work with the throttle twisted wide open, and seems to sing on all 4 cylinders at such times. But throttle response sucks for some reason. When the engine is warm , there is a big delay between blipping the throttle and getting the revs up. Winding off the throttle, it tends to want to cut the engine. Then, it doesn't idle. The carbs are clean, and it's likely I messed with the balancing settings when putting them back together (I separated them all fully). The lack of response to throttle blips confuses me though. If the balance is out, then it shouldn't affect throttle response when blipping at higher revs, but I'm not sure...

I'll probably be asking a lot of questions here on this forum.