super six how to tell if it is one

"Super Six" means 2bbl carburetor instead of 1bbl. The 2bbl air cleaner assembly does not fit the 1bbl carburetor or vice versa, and you've got a 2bbl air cleaner assembly, so while the carb, choke thermostat, and throttle linkage aren't visible in your pic, the odds are that somebody has in fact swapped a super six intake manifold, carb, linkage, and supporting bits onto this car. The 2bbl slant-6 was first available in the US/Canadian markets in '76, but was not offered on the Dart/Valiant/Duster.

The water pump bypass hose thing is not applicable to your car. That's a quick way of discerning a G-engine (170 cubic inch) from an RG (198 or 225); the RG has a bypass hose about 3" long, while the G has a bypass hose about 1½" long. In both cases, the diameter is the same; it's 5/8" heater hose. But the G-block 170 was replaced in the North American market by the RG-block 198 for the 1970 model year, so while it's conceivable someone could've swapped a '68-'69 170 into your '73, it is not likely.