^^ Correct. Instead of being .030 over, it's .040 to make 308CI (using the NHRA formula of bore x bore x stroke x .7854 x the number of cylinders = cubic inches).
how much can you take out safely without making the walls too thin??? why 308 also?? was the block damaged slightly and had to use the extra taken out???
I've always heard .030 for a stock block, .040 being the max. You can go up to .060, but you'd really be pushing it and it's not recommended because it makes the cylinder walls pretty thin and doesn't give you any room for more boring without sleeving the cylinders.