Thanks Vince!
Yup that shall be plenty to grip on in a 4 jaw
I use to be a cnc machinist, and the Co I work for has quite a large machine shop most of it has been decommissioned though these days.
When I was 17 as an apprentice, one of the many machines I operated was a horizontal borer machining large forgings and we use to do up to a 60T forging (prop shaft for the frigates) and the chuck on that machine was bigger than me (I'm 2 meters in height)
Sounds crazy but to bore a 300mm hole in the prop shaft use to take me a week in one cut, the shafts were something like 12+ metres long!
A flywheel from the N54 isn't overley large in diameter in our machine shop