I figured the 742 as #1 since the SG clutches can be rebuilt and beefed up whereas the 489 not easily refurbished
Hang on friend;
the Cone-types are just as easy and usually cheaper to refurbish, than the clutch-type; and on the street, when properly set up, I kindof prefer them;
and they fit in any case with the correct bearings.
I have done several, with success;
and still have some in stock.
I normally run 742 cases behind my HO367, that by the math, is making over 400 hp., and I have been running 295s back there for over 20 years.
At one time, I had at least one of every rear ratio from 2.76 to 5.13; except never had 3.73s, nor 4.56s.. all of them installed in whatever case, and most with the Cone-types; all set up by myself. IIRC only my 4.30s were in a 489, and with a Trac-Loc. I mostly ran those at the track with 325/50-15 BFG, Drag Radials, so I wasn't taking any chances. At first, I ran those with a spool, but one weekend is all it took to convince me that a spool on the street with big tires was NOT for me.
OOPs!, late to the party, yur all set already