If you have the rim in hand you will do yourself a service by measuring the erd directly rather than relying on the published spec. I have measured plenty of rims in my 3 decades of wheelbuilding that have not matched the specified erd. In one case, only a couple of years ago, the actual spokes ended up 4mm’s shorter than if i had used the published erd.
If you aren’t confident in measuring it a local bike shop should be able to do it for you, and supply the spokes if you need them. They may do it free even if you don’t buy the spokes if you have a good relationship with them.
Correction: I looked through my notes, and it was the ERD that was off by 4mm’s, so the spokes would have been 2mm’s too long. Still, maybe enough that the threads would have bottomed out before the wheel was up to tension.
Thanks J, I had already measured them, just looking for for some type of confirmation on my measurment before ordering up expensive spoke sets. My luck over the years has been different, usually when I use the mfg published specs the spoke length comes out right on the money.