I'd just hate to see holes drilled into the stick or front crossbeam just to hang a boom so you can hang an old used sail, but that's just me. YMMV.

I...guess... you could just hang any old sail whether or not its set up for boomless just to get used to the boat...um... maybe.

But it's not a matter of just adding a boom. You have to consider the relationship between the clew and the traveller or you'll end up with a hopelessly misshapen sail.

Some Square masts are 31' and some are 30'. The stock NACRA Squares had 30' masts and some folks (like me) added a foot to the stick. The sail in the eBay pic looks like a rather old stock NACRA Sq main which likely will be 30'. edit: you say the mast is 32'??

My advice is. Seriously. Absolutely. Get a sail made for THAT boat. Just as she is. Don't make changes before you've seen her performance as she was before you got hold of her.

Is this boat Virl Eichmann's?