Ah Yoshi 823 I didn't realise you'd posted here, it was your thread on BCF that set me after an F2 in the first place! Yours was a stunner shame, how it ended up.
Acquired a spare set of barrels for the 750 that were a little damaged, came with the 65mm pistons to take it up to 836 if I so wish.
The damage.
Chucked them in the works oven at 85 degrees for about 20 minutes then proceeded to tap them out nice and easy.
3 of the fins on one side were also damaged so welded them back on (bottom left).
Little bit of filing and they should look as new, provided my contact in Middlesbrough gets in touch I should be able to get some NOS 836 rings so should only cost the new sleeves + machining of and soda blasting and I have a cheap 836 kit (fingers crossed!)