Either one will give you a boost in power. The 318 has smaller intake ports on the heads so the ports won't match up perfectly but it will give you a bit more power. Swapping in the 360 will definitely give you a lot more "seat of the pants" feel and it will pull loads around a lot easier. None of the '70s era engines are powerhouses in stock form but all have a lot of potential. Even the 318 can be built with the usual mods to make respectable power but many would consider building a 318 a waste of time if there is a 360 available to be built. As the old saying goes, "There's no substitute for cubic inches" and with the longer stroke of the 360, it has a lot more low end torque. If it were me, and the 360 is in good condition, I'd swap it in as it's an easy bolt in deal and will feel about like you have two 318s under the hood. If you don't like it, or later want to swap back to the 318, the swap only takes a few hours.