Update...

I left them in water overnight and about half of them sank. Are these viable?

I hope you got them out of the water and let them dry out. I've seen other posters leave seeds moist for too long and they start to sprout. Floating could be a sign of bad seed since it would mean they are light. I've never tried floating seeds to test for viability.
With melons and squash type seeds it is pretty easy to tell the good from the bad. Good seed is plump and unbendable. Well they will break with enough pressure, lol, but withing reason. Bad seed is thin and bends easily.
Remy