I was looking at the differences between Bins today and decided to check out a 305 TPI's chip just to see if there was a difference so I looked at the AXXF bin which is for a 305/Auto car with speed density and TPI and compared it to a stock AUJP bin. I found that the VE tables were the same, but the AXXF bin had a much more aggressive spark advannce table than the AUJP for the 350 motors. Is there a reason why GM did this? I know that the LB9 and the L98 have the same compression ratio, and same camshaft specs in 91-92 but both used iron heads and both have the same fueling curve? Has anybody ever tried running the more aggressive SA table from the 305 on a 350 motor?

IIRC, a larger bore requires more advance for obvious reasons... and since the main difference between any 305 and 350 is the bore, that may explain the differences you saw.