Yes, thanks.
I have just done my first test with:
75% methylated spirit from the builders warehouse (the blue dyed stuff)
10% unleaded gasoline
15% castor

My old Irvine .40 ran anywhere between full wack to medium idle WITHOUT glow battery!
The throttle response is very sensitive and unless done slowly just kills it, but I haven't done any proper needle tuning yet (it has an idle one too).

If/once I get it running more smoothly, I will add more gasoline to see what happens. I see no reason to use more than 15% castor on this engine because it's fairly loose and castor is more expensive than the other components.