lots of choices. the easiest swap/upgrade will be a late 235. almost a drop-in and they can be plenty reliable. a 250 is a good choice but lots of things to change as that engine series mounts differently and requires a different
bellhousing , etc. a small-block V8 is a good choice but again lots of things to change. your 216, if it still has the original engine can be built to be very reliable. if you want to go fast then brakes and steering must be addressed as well. Safety First. do lots of research on this site and others and make a plan before you jump-in and start changing things.
Above all Welcome and Good Luck!
