Modern catalyzed polyurethane is very hard and tough. I can't imagine there'd be any audible difference compared to Lacquer. There's much more difference in damping between different cuts of wood, but the Ebony FB makes the attack brighter than Indian RW, and the Maple/Mahog body is so dense the type of finish shouldn't matter anyway. Lacquer discolors and cracks more easily. I'd go poly.
One advantage of a TOM bridge is you can raise the tailpiece up or down to alter the sound of the strings via the break angle. I set the high E side up to where the string almost buzzes. It gives the thin strings a fatter sound and more sustain. You can also wrap the strings over the TP if you want to keep it down lower. Different bridge materials have a substantial affect on tone/sustain. Thicker saddles were key to that late 50's LP sound. An Aluminum TP allows more body resonance, which can give the guitar a "looser" response, and maybe less sharp attack, as the more resonant Al absorbs more upper-mid string vibration, especially with a more shallow break angle.
I have one....As good as any Gibson I ever owned!!! Bad ass fiddles!
