The 3.27'a are a great way to go. I would completely avoid the 3.55's......the first gear in that set-up is a total waste of time. Don't go higher than the 3.27's.
Just my .02 worth
1997 LX Sport 4.6L 2.73 , MODS=SCT tuned/J-Mod/Trans Cooler/Dyno max Cat-Back/NgkPlugs/Mac cold air/March UD's/FRPP aluminumcarrier3.73's(spare for strip use)/ PI cams + PI intake manifold w/adapter plate/ Mark VIII Convertor/80mm L-Maf/70mm TB/ Mark VIII 1 piece shaft/Cobra R' wheels/ Kumhos 235/60/16 - White leather w/ blue cloth seats - white face gauges in 95 cluster