I have about 600 in stock and you should gap them to 0.65mm
However, you would do far better with a set of denso iridium IK27's.

With regards your friend reading the plug colour and advising engine mixture conditions, did he ask you for a detailed explanation of engine run time and load and then ensure that you cut the engine dead under load and coasted to a halt before removing them from teh engine? If not, with all due respect, ignore any mixture advice he gave you.