Started to mount up the bellhousing today and guess what, it has a few issues.
First as I already suspected I have around 6mm of interference between the crank and the gearbox input shaft.
Next the slave cylinder needs about 10mm or so spacing out to line up with the fork. Might try using a BA clutch slave and see how that goes. (Edit: closer to 15mm out and moved forward about 15mm also)
The bellhousing fouls the firewall on a starter mounting tab on the bellhousing that is not even needed, I was tempted to grind it off but moved the firewall out of the way a little.
Lastly and the worst bit is the BA starter won't go all the way home into the bellhousing, it fouls the inside of the casting. looks like the CNC had a spell while it should have been doing this bit....Rang Dellow but no answer on a Saturday.
Can't say I wasn't warned about Dellow.