Tally the bearing is standard 607zz with a rubber seal
you can use any bearing of that style. all pre NS model novas, and rb's use that bearing it is very common. Os uses it to. I'll get you a number so you can get one from tower.

I see alot of talk about bearing leakage these days. so let me dispell a myth. They all leak slightly no matter what your running these days. The long intake timing and short pipes everyone has gone to to get smoking performance causes this. the blowdown and subsequent pressure rise in the crankcase causes a small amount of fuel to be pushed out the front. And if you run the engine to rich it will really leak. The other issue is that at the rpm the engines run at the seal can go away really fast. I used to keep replacement seals in my box and changed them as a maintenance Item on my novas. Thats just the way it was.