Don't waste your money. Either live with the 6 for what it is or pull it and put in an 8. You will never make the 6 equal to the 8 and the parts to improve the 8 are much more plentiful and much cheaper.
I have had a 250, a 292 and a 350.
I like my old 292 well enough but if it has to be rebuilt, it is going to get swapped for a 350 real fast.
