I would have to say that the Spindles are probably no-mans land as far as weight reduction. I think there are some 72'-73' Spindles that have less mass in their casting and thus far lighter by a pound or less. I haven't found them to compare against mine though.
About the only thing that can possible be done there are the two massive spindle mounting bolts and nuts in Titanium, along with about 16 castle nuts in titanium. EX$penSive indeed it would be.
I'm saving my wooden nickels.