You could start by PM'ing me with the name of the previous owner(s) if you happen to have that info. I'll check and see if it's one that I've done on my travels.
The airbox lid will confirm Full Monty but not Ivan's Slip-on kit installation. The choke/no-choke starting might be a clue but isn't reliable enough. Likewise, roll-off/roll-on in top gear isn't bad with the stock carb set up.
To be certain, you need to check one of the carb needles. No 2 carb is easiest to access with the tank up. Remove the carb top (2 screws) and lift out the diaphragm and slide. Remove the needle and if it has SD-129 or SD-130 stamped around the top, it's a standard needle. If it's not standard, take a photo and post it here - I'll be able to identify it for you.
Mike