we don't know about his 5k potential in '99 when he ran that 7'23 ( he ran his 12'50 in '03, when he was more interested in the 5k )
it's possible in '99 off primarily 1500 training he coudn't crack 12'50 at the time
also in that 7'23, he ran 1st km in 2'28, which was a bit slow ( 7'24 pace ) & then kicked in a suicidal 2'25 which killed him for the last km ( testimony to his quality was he only really showed his fatigue in last lap or so )
probably shouda gone about 7'21 that day if he'd paced it properly
interestingly, if we offer him 3'26.0 / 12'50 - 12'55 in '99 :
3'26.0 / 12'55.0 ->7'22.6
3'26.0 / 12'52.5 ->7'21.7
3'26.0 / 12'50.0 ->7'20.8
last 2 lines look about what that 7'23.0 race looked like if he'd run it sensibly