Thanks Ian, I'm trying to visualise this.
So you are having a new Flywheel made that will have it's friction face further out from the crank end to match the original position of the Toyota clutch/flywheel interface (and this is 20mm because that's the thickness you need for your adapter plate). And the new flywheel will also have its starter teeth/ring gear in a place to suit the original Toyota.This new flywheel will have a bolt PCD pattern to match your Ford V6 crankshaft. It will have a friction surface to match the original Toyota clutch you are going to use. The nose of the Toyota gearbox will be supported how? I guess either a bearing in the crank elongated by 20mm or by an extension of the transmission shaft. Or perhaps the transmission shaft is long enough anyway or isn't supported in the crank?
Wow - its a lot to get my head around and that's without even thinking about the clutch actuator!
Clairetoo's locost posts and her company Crap Engineering make an adapter to fit the Mazda V6 to the Mazda MX5 gearbox that looks like this:
as you can see the position of the starter causes a few headaches in this setup. She chooses a spacer on the crank to avoid having a new flywheel made and because she wants a light flywheel.
cheers
Ross in NZ