Grab 'em! The Stinger 75 was a mid-1970s-early 1980s model. I've got a 1980 with the checkered flag hood. Love it! Had it for 20 some years now, rebuilt it when I bought it in the mid 1990s with fresh bores, new pistons, rings, carb kits, water pump, etc. Other than replacing the water pump couple times for periodic maintenance, and having a power pack go on me, it's been trouble free. Oh, and I did have to replace the trim solenoid once as the old one got corrosion in it (transom mounted solenoid box got damp).
The OMC 3-cylinders are solid design, with the 75 hp, 49 cube models being among my favorites. 1978 & up gets you newer style power trim, or the ability to add it if desired. The mid 1980s era 56-cubers had some issues with cooling the block properly, but I believe they got the issues worked out with some updates.
Bottom line, if the complete motor is basically healthy (good compression across the board, no water in the lower unit), then go ahead and put carb kits, hoses, water pump into it and run it!