As a guy who ventured under 11 seconds FAT in high-school once this was done with a ton of weight lifting and literal effort to keep mileage off my legs in order to preserve pop for the jumps. I was able to piece together a solid 400 and 800 but anything more than that was an absolute no-go.
I have a lifetime goal of trying to crack 2:30 which I would consider a serious stretch goal so I guess I would fall into this category were I able to pull it off.
For my genetically mediocre self it would be basically impossible to do anything close to both simultaneously. I agree with others that a gifted 1500 specialist might have a shot. I have to think a 3:30 guy could probably go 1:44/
47.xx/sub
11 and could probably gut out a sub 2:30 marathon at the same time. To use an American household name I would guess that Alan Webb in his prime could do this. In fact, I would be blown away if he couldn't.