289s and 302s were pretty much bullet proof. I've never heard of any casting problems with the 289 that resulted in a thinner cylinder wall. The 289 and 302 share the same bore and I don't think there is any difference in that area of the block. The 302 might have more meat in the bulkhead area but I'm not 100% sure.
I do know that all american manufacturers began to reduce the nickel content in their blocks starting in 73 - 74. This means the wear characteristics in the bore area are not as good but still, these engines made good performance engines. The cylinder heads on 73 and newer models were junk as they had tiny valves and ports but there are no sginificant problems with the blocks.

 

The 289 and the 302 have the same cylinder wall thickness. Now, the earlier 221 and 260's had a thinner wall, and could not be bored out to equal a 289. Maybe that is what you are thinking of.

 

I was thinking of where i herad that. I know where i made a mistake. I read it was unsafe to bore early 289 block to its maximum bore because of a water jacket location causong problems.
Sorry for the mix up and thanks for clearing it up for me