Worth bearing in mind that altitude for a 400 may not have that much overall effect.
The lower air resistance is somewhat offset by lack of oxygen which impacts the significant aerobic component of the race.
Anyhows, that indicates certainly around the 48-flat mark at sea-level on a synthetic track ( if you use 1s/lap conversion between dirt/synthetic )
Now, at his 800 peak he was a 1'43-flat guy ( 1'43.17 in his 1st serious 800 has to be worth quicker if he'd run some more top field 800s that year as he was a newbie to 800 )
There isn't really any point trying a any calculator at this point : 48-flat & 1'43-flat are pretty much what was expected of Hicham.
Now, I don't anyway believe his 1500 potential was anywhere close to 3'26, so it does indicate Asbel shoud be a bit quicker than 48.0 at sea-level ( I'm talking in '08 or 1'43 year - He may be slower over 400 currently than he was back then )
1'43.0 with
47.50 ->3'26.8
47.25 ->3'27.6
47.00 ->3'28.5
Realistically, at his peak ( maybe Peking '08 or in his 1'43 season ), I think low-47/47-flat was better indicator of his 400 ability.
As for those 1500s - they are purely hypothetical - Canova has stated that he just doesn't do the endurance work to get anywhere close to those potentials