Dual curve is an add on box which allows you to advance the distibutor base timing when on lp then it limits it on the top. When you switch back to gasoline it "retards" the advance that you dialed in back to gas std timing. I would do a general port/polish
I use to recomend stellite seats and sodium filled exh valves but with an unleaded motor your half way there. Just remember LP is approx 125 octane it needs a hi intial advance then be limited to 32 or so on the top. Of course that assuming stock cams etc. If you have the facilties and the time you can play uite a bit but it may not run on gasoline hence the dual curve.