The Balancer that came with my '75ish 350.. is about 3/4" thicker than the one on my '87 305 block. Between 305 and 350 in '87... the balancer is the same....

I am putting this 350 in place of my 305.

If I use the balancer from my 305 again... the timing marks wont line up.... If I use the balancer that came with my 350... the crank pulley is going to stick out far.... what do I do?

Is it important that I use the thick one that came with my motor?

My crank has drilled out parts I think are for balancing, and the flexplate didn't have any big weights on it that would imply it's externally balanced...

Will I be okay just using the '87 305 balancer and create a new timing mark?

 

Use the thick one.

The pulley mating surface is the same depth. The extra thickness is on the back side, towar the timing cover.

Al SBC balancers, from the ones that weren't balancers at all but were only pulley flanges that came on 265s and 283s to 400 ones and 8" 350 ones, locate the pulleys in the same plane.