Danny
I hate to burst your bubble, and I don't know where you got your '64 389 HP numbers, but the '64 GTO with a 4bbl had 325 HP and the tripower equipped version had 348 HP.
There is a reason that Royal Pontiac pulled the stock 389's out of the Royal Bobcats and dropped a 421 in.
I seem to remember an old adage that goes something like this...
There is no substitute for cubic inches...
Well maybe a little NOS...
