340 w/ 727 auto won't turnover

If you don't have a multimeter, like when away from home, turn on the dome lamp to use as a poor-man's voltmeter. If it dims a lot when trying to crank, then there is a large voltage drop across the BAT+ or BAT- terminal, or the battery is weak. Measure the voltage difference right at the battery, i.e. probes right on the lead posts. Measure again on the cable sides. If much lower, clean your battery terminals. Try turning the engine over by hand to assure no hydrolock or such.