Circa 1983/1984. Like most most manufacturers, Shogun made multiple models from a single frame by varying the components. If it does not have brazed-on down tube shifters, it is a 300 or 400, in which case the wheels are 27". If it has brazed-on down tube shifters it may be a 550 or 600. Bottom bracket will be English threaded, but the spindle length will depend on the chosen crankset and hubs, to establish the correct chainline.