What were the valve stem diameter, 3/8" or 11/32"? Nice advantage to using the LS parts is availability and cost. Because the General has built millions of those engines and installed in full size trucks and SUVs, they are everywhere.
If you install 5/16" valve guides and hone to fit the 8mm LS valve stems, or get 8mm guides, the valves are lighter and the retainer is lighter. On top of that the top of the beehive is small diameter so less reciprocating weight there also.