I have an 8yo 56lbs.. is it ok to give him cold medicine for congestion and ibuprofen for headache at the same time?

Yes: It is okay to give him age/weight-appropriate doses of over-the-counter cold medicine and Ibuprofen together...As long as your cold medicine also does not contain ibuprofen. Check the label's active ingredients.

Generally yes: As long as the cold medicine does not contain ibuprofen, combining the 2 should be ok. That being said, many pediatricians do not like cold medicines for young children. They're not very effective, and the side effects are relatively stronger--anti-congestion meds are generally better at stimulating the heart or making the children alternately drowsy or hyper than they are at treating the cold.