89 owners manual reveals the following about the Chevy 454
There were two 454's. Both were 7.4 litre. One was coined an HO. Here are some specs.
Both the same
Displ. 7.4 / 454 CID
Bore & Stroke 4.25 x 4.00
comp ratio 8.8:1
Fuel Sys Holley 4 barrel
Not the same
RPM HO version turns 200 more per min. @ 4600
HO was a left hand rotation only.
Net weight of engines are identical.