Thread is old but pretty interesting.
Rudisha ran 45.5 in Sydney, clocking 1:43 afew weeks later. He ran the WR 1:41.01 later that year after introducing faster work so his 400m time had to be around 44.5 at the timee of the WR.
The conversion rate for a 400m runner who is highly conditioned is best 200x2 plus 3 seconds which gives Rudisha a 200m of around 20.75 at that time.
For the 200m typically a slower runner stuggles to start off as quick so the second 100m is around .5 faster than the first so in that regard Rudisha would have been running around 10.6 for the 100m aswell.
Btw Marcin Lewandowski has clocked 10.61 into a -.4 accroding to the iaaf profile so a similar time is highly possible for a superior runner.
I would say Rudisha would never get the 10.6 but 10.3x is possible, giving him around 20.3 and 43.6.
I was watching a show on BBC a while back where Colin Jackson was saying how shocked he was that Kipketer beat him in a training race over 100m so i probably think that his best recorded 400m time is inaccurate aswell