Alex, I carried out a 1.6 to 1.8 last year.
If your budget allows then go for the lightweight flywheel, it transforms the character of the engine.
You will need to increase the fuel pressure from its current 3bar to 4bar. You can either buy an adjustable fuel pressure regulator or squash your current 1 in the vice. The one that came with the 1.8 will still be 3bar
I did have issues with lean running when I finished even tho my fuel pressure was up at 4bar. I would suggest taking it to a rolling road once you have finished to get the fuel mixture checked. I've now fitted and Emerald ECU. Others have had no issues, do a search in tech talk.
Gareth
Blue and Carbon 6 Speed 1.8 Supersport here