Starter part number and date code will tell you the application it was for
NAPA or other FLAPS have cross references to the part number on the existing starter. Nobody will be looking thru a lot of boxes. There are maybe 2 or 3 starters for late model 350 small blocks. The newer the engine the less choices because for late models with low compression there was no need for a heavy duty starter. Generally in the past there were maybe two starters for a given year or group of years a heavy duty and a standard duty. In 1975 there were only two Corvette OEM engines the L48 (base) and L82 (HP) neither one of which had a compression higher than 9.5:1 so there may be only one starter. Educated guess says your engine is later(newer than 1975 and low compression.
What are the numbers on the starter you have? Delco Remy (GM) Electrical components (starters, generators, distributors, coils generally have a number starting with a 1 such as 1100694(1967 small block alternator) For 1967 all small blocks used the same starter(1107320)
Likely NAPA will have two replacement alternatives for your starter a new replacement (non OEM) and a rebuilt OEM part. If you are not doing a numbers matching NCRS judged restoration(which you can't with your current engine) a replacement starter of the same design will be just fine.