71 engine pulley help needed

[Mowdigger]

I posted this in the engine forum and haven't had any response. My truck is a 71 C10 2wd, auto trans , and originally had a 307. I recently replaced the 305 that had replaced the 307, with a 350 out of an 85 suburban. Today I started putting the pulleys from the 305 on the 350 and I believe I ran into a clearance issue between the harmonic balancer and the water pump pulley. There doesn't seem to be enough clearance between the two. Now, the harmonic balancer on the 350 is an 8 inch compared to the original 6 inch balancer. What are my options ,so things will run corectly? Are there different diameter water pump pulleys that will work? shoot me some input , I sure would appreciate it.

Mowdigger