Thats not too bad, dont' forget the V4's are lumpy anyway and it's old, what are your valve clearances like?

Valve clearances are pretty spot on, well within tolerance.

The reason I suspect the inlet rubbers is that the rear ones are a bit on the tough side whereas the fronts are still quite supple.

Could be your pilot screws too.

What exhast system / mixture setting at?

You can get some carb cleaner (the flammable stuff) and spray it on the rubbers while the engine is running, if the rpms change its leaking through the rubbers.

when it's running if you rev the throttle then let it drop back to idle, does it.

1. return to idle ok
2. drop below idle then come back to idle
3. hang slightly before going back to idle

Pilot screws are all set to two turns out.

When I blip the throttle, if I do it too quick, it will bog down and stall but I think this may be due to the engine being cold. Normally speaking there is a slow return to tickover and a slight hang at around 2.5k rpm. I think I may need to clean the throttle tube on the clip on and adjust the cables in addition but I still think there may be a slight air leak.

Hanging at that rpm is air-leak / overly lean mixture.

The stumbling when you gas it hard could be cold engine / float heights (what do you have them at)

It is possible to get a good running engine though, mine idles like a watch, accepts full throttle without stumbling so it is do-able.

Carbs can be award to get on properly, putting the rubbers in hot water before you mount them helps soften them up!

All float heights were set to 6.8mm when I stripped them. New air filter turned up today so that may help a little too. I'll check the inlet rubber clamps are tight properly before I start messing about taking the carbs off again.