pull the valve covers. if there are screw in rocker studs, the heads could be either hipo heads, or just modified. look at the dampner, it will be about 1/2" thicker than ac or a code 289. if you can pull the oil pan the main caps will be full thickness top to bottom rather than tappering at the top, sorry no 4 bolt main caps on the hipo 289. if the pan is pulled, also look for an add on counterweight right behind the crank gear. if the disst is stock, it will have dual points and no vacuum advance.