Have you contacted Holmes? They might already know.
If you buy a QS 205 50 V3, it's the same as a Cromotor which they used to already lace up, so you can order the ones they have on stock, which are 108mm.
They only sell 2 lengths of 10g spokes though, 108mm and 128mm.
That said, if you need other lengths of spokes, or gauges with the larger nipples, like I did for a different build. I buy them off ebay, from Kingstar https://www.ebay.ca/usr/kingstar-cn?_tr ... 7675.l2559
Worked great, no issues with them.