'Should be' being the operative phrase here but it no longer is. Due to the way I ad to fabricate the bearing mod, I can't just do that now, or more precisely I can, but I have to be careful the thrust bearing will be hit by the back of the blade before the centre of the bearing bracket. So if I just move it forwards like that then the blade would never get to the thrust bearing hence having to add washers. Won't be a problem now though since I've sorted it.
Also added a smidge of tension, and checked the lower bearings etc - tried again. It's made a gnat's something or other difference really - maybe a mm less than it was out by, so still a lot of twist going on.
So. I fashioned a thin bit of oak to 'clip' onto the fence clamp, and gave it a small central radius to rotate the fence about, within reason:
Clamped it on, and it worked perfectly! The fence now sits at the required angle that I'd marked. Also, it sits flat, and is capable of wobbling if you try, but nothing like it was previously. Ace!
So I did a test cut on a bit more of said oak, and on a 9cm piece it was 0.2mm thicker at one end that the other, so 1.4mm to 1.6mm over 90mm length. Not a bad starting point to be honest. I think a tiny bit of tweaking and I'll have it just about spot on, so when I get it to that, I'll cut a load of strips of stuff to use like this, before I end up moving the fence again. I'd scribe some guide lines onto the table but it'd be a waste as the next blade will be different I'm sure, so pencil marks will do for now.
Quite pleased with that though actually - might just have solved the first question I asked on this topic. 
Needs a slight sand to smooth one side of it then it'll be about the perfect thickness.
