I am 6'4", was 195 in college and ran :48, 1:49, 3:42, 8:48 (2 miles) and 14:22. Track and Field news included the 3:42 in their review of big sub 4 or equivalent milers in 1987. (Not popping off but throwing that out there for the inevitable naysayers who emerge occasionally on the site)
Currently 202 and 51 yrs old. Ran 2:06 for 800m 5-6 years ago in local masters meets. When I get warmed up and the wind is blowing just right, I manage 30 secs for 200M in trying to hang with my frosh high school daughter who is 5'10" and ran :59 and 2:28'as an eighth grader last year.
What I would share and what I built my program from was not worrying about the mass, but rather using the old Coe and Ovett premise that you would optimize your results by working hard and maximizing the strength and power of the muscles you have to carry. Seemed to work well for them. If you run enough miles and strength train, my experience is your body will find an equilibrium on its own. I was benching 275 regularly in college and had fun lifting with the football team occasionally.
I tried to get under 190 a few times during college and while I was lighter, I was definitely weaker so we gave that up and instead focused on fitness. I ran 3:42/3:43 three consecutive seasons so perhaps reached body limits given weight being carried.
Hope that helps -- good discussion, if my experience helps then that is a good thing. Good luck.