You might want to consider a few things before you get too serious with the cam lift......The factory 289 HiPo produced 271 HP and factory cam in this motor only had .457 lift......Unless you install much larger valves,the heads are at almost peak flow at that lift.....Going with a higher lift cam with more than 230 degrees duration will reduce your throttle response,kill your bottom end torque,idle rough as hek,and require at least a 2000 stall converter.......This is a fine example of why bigger is not always better.

   A cam with .460-.490 lift ,220-230 duration with about 110* of lobe separation will give you strong low end, a streetable idle,tons of  low end and mid range torque,and a good stong power to around 6000rpm.....Be there,Done that,and Have the trophies(RDW)