The titled motor was used in freshwater it's whole life but I want to use it in saltwater. mostly inlets which are brackish. Should I have any concerns?
The OMC motors, especially the older ones were made for saltwater use. Lubricate the grease fittings and other parts more frequently and have fun. I doubt there was even a recommendation to flush 'em.
You should flush the water intake after most outings otherwise you could get a salt buildup on the rubber water pump other than that just make sure your lower unit seals are good salt water would be really hard on the shaft and gear that is a fun little motor I have the 62 version myself