The 5mg Hydrocodone in Watson 349's is roughly comparable to 3.3mg of Oxycodone.
So it would take roughly 90mg of Hydrocodone to equal your 60mg of Oxycodone. That is equivalent to 18x Watson 349's. However, as previously mentioned, Watson 349's contain 500mg of Acetaminophen/Paracetamol in them so you'd have to do a cold water extraction on them.
This is of course assuming that your 60mg of Oxycodone is instant release, and not slow or extended release, and does not account for any incomplete cross-tolerance of the drugs.