I decided to get my engine sorted, so yesterday dropped it up to the guy who is doing it for me and handed over the complete bottom end. First susprise was that he informed that it is actually a 650 with thick flange barrels (its registered and insured as a 500 - will have to get that changed) Got an email today to say crank and rods are US, I gave him a spare crank that I bought as an A7 crank but it turns out it is an A10 crank, so thats a result. When he dismantled the old crank he was amazed to find the rods are large journal sitting on a small journal crank with 2 sets of big-end shells to take up the slack ! and a 1/8 " of end float
No wonder it was a bit vibey! I have covered nearly 2000 miles like that.
Surprisingly he has reported the rest of the engine is in good shape(cam,followers,bore is on +20 and in good condition) Looking forward to a much improved engine