Ahhhh Im to late! I would have drilled and tapped 3 1/4 24fi threads on the spokes as close to centre as possible (basically where your cut lines are)and used a puller as per the style we use on early Victa fly wheels.
Flys are around so its no biggy, especially since you would have the same issue next time round.
A fair outcome Giz, especially if the internals were saved:)
Ill give you a hand with your Roto shortly Mate:)
