i think most people agree, wariner is "shaped" more like a mid distance runner than a "true" sprinter, but then again Juantorena didnt look like a mid distance runner.
the womens 800 WR was set by a juiced to the gills czk or where ever the hell she was from, and was at one time the womens WR holder in the 400, with 47.99 i believe.
Juantorena had i think 44 low all out speed, Yury has 45 mid speed, seb split 45 lows and 46 low in the open. i dont think jeremy would have to change his current training very much to be in the 144-145 range. since most of his training is speed-endurance, workouts very similar to 800 training, lots of 200's with minmal rest in about 25-26.
400/800
juantorena 44.26/1:43.44 WR at the time
Norberto Tellez (CUB) 45.27/1:42.85
Yuriy 45.84/1:42.47
Patrick Ndururi (KEN) 46.09/1:42.62 gray 46.30/1:42.60 AR
Patrick Nduwimana(BDI) 46.32/1:42.81 Bucher 46.32/1:42.55
Frederick Onyancha(KEN)46.50/1:42.79
Kipketer 46.85/1:41.11 WR
Coe 46.87/1:41.73 WR at the time
so based off this, you could claim that jeremy could hit around 144.