600 monster issues

I'm hoping for some technical advice
I recently bought a 94 600 monster
The bike has recently been partially restored.
It was sat for a year inside and so far I have only managed to ride her the 12 miles back home .
She won't idle properly is hesitant and really down on power.
It seemed like she was running very rich with smoke coming out at idle.
So far I have

Replaced the old fuel
Replaced the plugs for standard champions
Cleaned and rebuilt the carbs ( but not the needle or emulsion tubes)
Check the resistance across both sides of the coils
And ran a compression test on the engine ( was well within specs)

I had her running after all this and still the problem remains and I then noticed what seems like oil leaking from the horizontal exhaust flange

I am at a loss to know where to go next
And any advice would be gratefully accepted
I just really want to be able to get out on her
Thanks