Hi Ben, nice work on the 650b conversion- it looks really good. Just about any normal drop-bar lever should work with Raids. The cable pull required is similar to most of the common rim brakes from the last three quarters of a century (v-brakes excepted, obviously).
Those levers look suspiciously like the Dia-Compe v-brake levers, one of the two drop bar v-brake levers available. Not sure where you heard you need long pull levers but that's exactly what these are. They will not work well at all with centerpulls because they pull too much cable and have too little mechanical advantage; they're designed for v-brakes, which have more mechanical advantage in the brake caliper and less in the lever. These will probably feel nice and crisp while you're setting them up, but in actual use it will take excessive amounts of force to slow the bike down. Any regular pull lever should be a significant improvement over these.
As for hood shape, the older Tektros were really nice, although the newer ones are not, in my opinon. They were also sold as Cane Creek and I think also Origin8. Shimano aero levers are my usual go-to, but they feel very similar to those Dia-Compes so maybe no good for you. Beyond that, some people remove the innards from brifters and use just the brake lever to get bigger and flatter hoods.
Good luck with the project!
Josiah
Missoula, MT