1973 Dodge Dart Slant Six Timing Chain & Gear
I can't think of a good reason to replace the timing set just on speculation, not with that low mileage. Go ahead and
check it (no disassembly required), but I doubt if you'll find much slack in it.
Keep in mind a low-miles '73 may still have the original not-very-good ignition module that can make random hard/no start conditions. You can put in a new module or, better, do the
HEI upgrade .