Man needs more speed.
If you’re coming from longer distances then what’s the point in doing lots of long reps?
You also don’t need to lift weights unless you’re not strong already.
If you already have good strength then lifting as a Master will just inhibit you, regardless of what they say about muscle decline in older people.
I’m in the middle of the 45-49 bracket and started competing a few years ago.
Ran only one 400 last year in 52.5s off 100/200 training.
You need speed, no point running lots of slow reps if you don’t have speed.
When your sub-max speed is fast, where your sprinting fast-relaxed, then speed endurance work will probably help you reach the next level.