The 289 heads have smaller combustion chambers, maybe, than the E7s plus you'll have to grind down the thermactor humps in the exhaust ports of the E7s. There are differences in valve size and combustion chamber size depending on the 289's casting numbers. Which heads are better than the E7s depends on this.
The rocker arms on the 289 heads use studs where the E7s use a pedistal mount design. The studs are pressed into the heads on the non HIPO 289s, but can be changed to screw in studs like the HIPOs. This is a stronger design than the pedistal set up. The rocker studs are 3/8" where the pedistal mounts use smaller 5/16" bolts.
The casting numbers are found on the bottom side of the heads. You may be wasting your time and money depending on the 289 head casting numbers. I don't think that there is much difference in port sizing with the later 289 heads and the E7 heads. | 
question bout some heads 
