By baffle, I am assuming you mean the SS plate between the outer exhaust cover and the block. I wouldn’t discard it just because it is warped when removed from the engine, this is what is usually found when these pieces are removed. The SS plate will be sandwiched between the two flat surfaces (block and outer cover), and will be flat where it needs to be.
In any event, I did find a new 319577 on ebay if you would feel better replacing it:
http://www.ebay.com/itm/OMC-Evinrude-Jo … Bq&vxp=mtr
And yes, there were many changes made to this cooling system in the early 80s, none of the pieces will interchange.