Surely you should consider the 800m, no?
Also I suck at starting blocks, I get into way better positions when I use a standing start, so I while I still work on my block technique in practice when it comes to races I just make sure I keep relaxed and efficient when I start.
Also I could show you videos of horrendous block technique and some of these guys have ran sub 10.8 / under 47secs in the 400m!
Point being, you have become completely disillusioned with blocks and the effect it is having on your race.
Keep working on them. In the meantime have a plan B for a race…a damage limitation as such.