Talking about the OP. I suppose it's doable an 4/8 type has access to more speed, which when given the proper endurance and aerobic/anaerobic capacity training would allow for an amazing 800 time. That being said, the half-mile/miler type has slightly stronger slow-twitch muscles which make holding a pace easier than a 4/8 type would, allowing for an amazing 800m time.
4/8 types would run somewhat less mileage (50-60mpw is a LOT for sprints and 800m training) and more focus on intervals and speed based workouts, which provides ample training stimulus for them since that's what their bodies tend towards. A half-mile/miler gets a better stimulus from including more mileage (60-70 and above) and longer repeats with fewer speed sessions.