I could use some advice on what to look out for when buying a used Norton Commando. I have owned a number of various makes in the past and have a general idea what to look out for but most makes do however have some vises and as perfect as I imagine the Norton to be is there anything I should be aware of ? (matching numbers noted). Also would the 850 be the better choice over the 750 or is there not alot between the two? Any helpful replies are appreciated. Regards Ron Western Australia