That balancer hub looks extremely rough, and there probably should be a deep, rapid spiral groove cut into it- - - -like maybe 0.010" deep, and 0.100" per turn on the spiral. I don't think I've ever seen a balancer without a seal with a surface that rough. Most of my exposure to those types of hub/slinger engines without seals has been on non-Chevy applications, however.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!