1992 ezgo marathon

[Family man]

Hello yall, first post here and hopefully get some sound advice. I have done a lot of research and found a lot of info on this forum but looking for a little bit more tailored to me answer. Im new to electric carts, had a Yamaha gas cart before. So, in a nutshell I have a 1992 marathon 36 volt series I believe. Got the cart for free with bad batteries dont know about the other components yet. Before I buy new batteries would it be worth going to 48 volt? I only use the kart 10 times a year on long weeken trips to campgrounds. Lifted with 22x10 tires eventually, me 260 pounds, wife 130 and 3 kids probably 250 combined. Not looking to run 35mph but faster than stock preferably. But when I hit the pedal I want it to go and not worry about hills. Ride times are just for 20 30 minites at a time so lasting days is not a requirement. Wjat upgrades would yall do for the best money. Keep in mind the cart was free.