I am in a similar situation as far as sprinting speed is concerned. 200 PR of 27.5, 400 59.5, 800 2:12, 5 K road down 1% grade at 4500 feet 15:37, 1:09:40 half dropping from 5800 feet to 4800 feet, 1:12:09 split in a sea-level marathon (Richmond), 2:23:57 marathon in St. George (2600 feet elevation drop), 2:30:32 on an honest sea-level course (St. Jude). I must add a disclaimer that I have not raced at sea level a whole lot and my best races in the marathon and the half marathon have happened on a downhill course at altitude.
I was able to run 59.5 at the age of 30, repeated the 200 PR from the age of 17 at the age of 30, and repeated my 18 year old 800 PR at the age of 37.
Over the course of the years I have tried to solve the mystery of low speed. A naive explanation was slow twitch fiber dominance, but I knew that was not everything because if it was the true slow twitch problem, the 800 would have been around 2:05, and 5000 around 14:30. Instead, even when I ran 90-100 miles a week, I was still slowing down from 400 to 5000 more like a middle distance runner with good endurance than a marathoner with no speed. Plus, I had a VO2 of 75.9 measured in a BYU lab which suggested a very poor running economy.
My form has always had an apparent awkwardness, but nobody has been able to coherently explain why. Different specialists made their guesses along the lines of some muscle being weak or tight. I would strengthen and or stretch that muscle greatly improving the strength and/or flexibility with no measurable results in running speed or economy. At the age of 39 I finally figured it out. An X-ray of my spine revealed spina bifida occulta in L-4 and L-5. This condition has been mostly asymptomatic for me as far as the general health is concerned - I did know if that if I ran too much around the track or a skewed surface, I would develop pain in the lower back, but otherwise I was OK - have been running now for 31 years with the longest break of 3 days, can handle 90-100 miles a week on asphalt no problem as long as it is straight. But this vertebral deformity, which affects around 10-20% of the population, is apparently enough to limit the top speed, as well as the running economy.
I have a strong suspicion that generally healthy male runners that try their best to improve their top speed but are stuck around the 60 second quarter barrier likely have something similar limiting them. If your form looks awkward, you feel glued to the ground, you can drop your competition on a downhill but they drop you on the uphill, your quads tend to overdevelop, 60 second quarter is a challenge, and in spite of solid endurance training you struggle to run a negative split in any race, it might be worthwhile to examine your spine for some pathology.
Unfortunately spinal deformities of this kind do not have a fix known to science today - from what I have been able to gather at least. It is my hope that an unexpected breakthrough in medicine might allow to insert something in the vertebra non-invasively enough so to actually improve your spine performance and allow you to run more competitively after the procedure or treatment. But for now your best bet is to keep the weight in a healthy range, maintain your overall health, train to preserve your endurance and muscle power, and keep the back and abdominal muscles strong so you can at least maintain your strength.