Is it safe to take nabumetone with ibuprofen for pain?

Not together. Taking two non-steroidal anti-inflammatory drugs can cause gastritis, gastric ulcer, including gastric perforation. So, in general , the answer is no. On the other hand, assumning a single dose of Ibuprofen (800mg), with its half-life of nearly two hours, should be "completely" eliminated in 10 hours. Nabumetone, however, has a half-life of 20-24 hours is not "completely" elimininated for 5 day.
Should avoid . Nsaids increase the liklihood of complications including GI probs including gastric ulcer and GI bleeding. May also inc the liklihood aggrevation of blood pressure, renal, and liver dysfunction.