Mark, That paragraph is only stateing what to go by when ordering and not the particular one he is ordering. He is ordering the one in the specs below that paragraph.

All Chevy small-block and big-block engines with one-piece crankshaft seal require an externally balanced flywheel or flexplate. Find the right part to match your engine.
Year of engine: 1979-90
Outside diameter: 12.75"
Crank flange bolt pattern: 3.58"
Clutch diameter: 10.4
Starter ring gear teeth: 153
Technical notes: Lightweight nodular iron. Counterweighted for externally balanced 454 engines. Use with balancer P/N 3963530.

I believe that would be the correct flywheel.

Fixx
 

mark,,all big block flywheels 1 and 2 piece seals are the same bolt pattern..


john have your brother use a bravo inner plate,,you will have 2 extra holes in it..this way you could use the bigger flywheel..if he use;s the smaller flywheel thet are harder to turn the engine over and hew will also have to change the starter..

Mike...I told him...stubborn 54 year old little brother...thinks he knows it all LOL!!

The bolt pattern is but the weight is not the same.

then there is always the half-a$$ option of the little add-on balance plate to a neutral-balanced wheel. i didn't now anybody made a 454 small wheel...you wwill need a serious starter. buick 455. rebuilders number is 3567. or take 3664 low-torque chebby starter and put hi-torque armature and field housing in it.