Actual compression of a 68, 340?
i hear they were around 9.8 to 10.1 not the 10.5. i don't think they were much lower than that. the 10 to 1 BB were the same about .5 lower then advertised. by stock 383 was 9.4 with a .040 gasket with the .020 that would have made it about 9.7 from factory. but one side of the block the pistons were all at zero deck, the other side started at .005 under and got worse towards the rear of the cyl, so the machining was sloppy