Carlo, since my HyperDrive 20 Mac is a Macintosh 512k with the "512k" label on back and with a stock Macintosh 512k board that has never been swapped out or upgraded, I am happy to answer your question. First have a look at this web page and search for "820-0141-A". That is likely the PCB revision you are looking for and is exactly what I have, as shown in my photo here. That PCB revision was made to either be a 128k board or a 512k board, and there are two white silkscreen boxes on the top side of the PCB that are used to mark which board it is (either 128k or 512k). (That Chinese Mac web page also talks about revision 820-0086-F, but I cannot say much about that since I don't have one. Mac128 asked about this "F" variant in this old post. I see one currently on sale at WeLoveMacs though.)

So if you want to find a 128k board that is stock to your Mac's plastic housing, then you probably want 820-0141-A or the 820-0086-F. Perhaps someone more knowledgeable that I can tell you the difference between the two. But I don't think you are going to increase the value of your Mac though, whether you put a revision 820-0141-A board in there or a revision 820-0086-C board inside. The original 128k without the 128k badge on back is the original from 1984 and carries the most value.

Henry, I'm dying to have that MacDraw file!