Perkins 6.354

Hi, I have an old forklift with a Perkins 6.354 that I took to a shop and had it rebuilt @ 2 years ago. The engine burns oil and I thought it may need time for the rings to seat. Any idea why it continues to burn oil? I was thinking of removing the head and checking the valves, guides and seals. Any ideas? thanks

Perkins 6.354