I'm 5'8 and 145 ibs, I can't imagine being almost 6 foot tall and weighing less than what I do now(outside of the running dysmorphic community, you are too skinny) . In my experience, trying to reach some arbitrary weight just results in not being able to train as much and more time on the couch being injured(for example in high school I always maintained a weight of about 115-120 ibs at my current height. Guess what? I was always injured and very fragile. Now weighing extra 20 ibs I am more stronger and almost completely injury free since getting heavier/stronger). Me personally, just follow Sara Hall philosophy. Do not focus on the scale, focus on training and eating right(but don't go overboard and become orthorexia.).
https://www.runnersworld.com/news/a20864045/racing-2-marathons-in-5-weeks-sara-hall-is-not-afraid-to-test-her-limits/
What people forget is everyone has different genetics. While Kenyans and Ethiopians can be 6'0 and 130 ibs, they have different genetics from Europeans(even within Africa certain ethic groups are bigger and more muscular.). Europeans due to evolution usually require to be a bit heavier to be healthy. For many different reasons, such as body fat, muscle, bone structure etc. A few professional runners around your height, a few heavier, and a few lighter.
Rod Dixon 6'1 and 154 ibs
John Walker 6'0 and 160 ibs
Lopez Lomong 5'11 and 155 ibs
Chris Solinsky 6'1 and 165 ibs
Ben True 6'0 and 164 ibs
Paul Tergat 6'0 and 137 ibs
Abdihakem Abdirahman 5'11 and 133 ibs
Alan Culpepper 6'1 and 130 ibs
Galen Rupp 5'11 and 134 ibs
Can't find the article anymore, but there was a good article about Ben True talking about how if he tried to loose any weight it didn't work out well.