I'm very similar size. Now 5' 8" and 148-150 range. Have been very similar for whole adult life (I'm 62, so was maybe a 1/2 inch or so taller at some point). I ran my best 800m at about 148, about 35 years ago, and never have got down to significantly lighter, even training for a marathon.
I'm sure I would have run better with a lighter build, but I doubt I could have got more than another couple of lbs off, and keep up energy to train. At 135 with my build, I'd be more likely to head to hospital than out to train...
Not much point comparing with elite marathon runners who are in part elite because they are very lightly-built. More a question of finding a stable weight which is low body fat, but not so stripped down that energy starts wane and the immune system is compromised.