Since we're sharing specific links now (and boy do I LOOOOOOVE "specifics"), I think it's necessary to share an exact link to that board. But the only link I can find is the a variant of the board that is larger...(Also, I didn't know you made that little board! That's cool!)

SE to 128/512/Plus Adapter - Joe's Computer Museum
Want to use the awesome SE-COMBO - MacPicoVid Edition in your Macintosh 128, 512 or Plus centered CatMac project? Well now you can with the SE to 128/512/Plus Adapter! The adapter takes the Macintosh SE pinned "J12" connector located on the SE-COMBO - MacPicoVid Edition and converts it to a...

QUESTIONS for @Ron's Computer Videos:
1. Is there a specific use case for the smaller board? If so, where can it be purchased?
2. What are the benefits of the larger board sold on the JCM website?