It more depends on budget at this stage, how much are you willing to invest? A good thing about an’18 is you can make a pretty good combination for not a whole lot of money. Do you already have an engine? While not mandatory for a good build, a 68 to 74 truck motor with a manual transmission usually has a steel crank and thicker cylinder walls, if you stumble across one. But any garden variety 318 is good for your purpose.