The R400 levers are, IIRC, modeled on the 6403 brake lever body (Shimano 600 level, Super SLR tech/geometry). They are really nice. I may not be a fan of the grey trim ring (prefer all black like the R600 levers), but they look good, are comfortable (I put a piece of bar tape on each side under the hoods to bulk it up slightly, helps a lot), and work well. Hoods for 1051 levers will be hard to come by, but it takes years to wear a hood out. They'll be all black with a silver blade. They'll look more 'period correct' but the body is narrower, so comfort will depend on how you set up your bikes. I will always suggest the discontinued Tektro R200 lever. Super comfortable, round, wide lever body (Campy 9/10s Ergo shape). Black with silver blade, good lever action, with a Campy-like brake cable release/slack feature for tire removal.