It's 8". That's the same for all 69 and up 350s and 400s. Although the 400 balancer is different since they are balanced externally, they still have the same 8" diameter as the rest. So that theory doesn't hold water.
Not 302 specific. Only 8" balancer specific.
SMALL BLOCK CHEVY 350 EARLY TIMING COVER DATED 10 | eBay
They are easy to find. Chevy used the 8" balancer from 1969 to 1980 on 262, 267,307,350 and 400. They made "a few".
