Asking for Advice Fix 273 or Replace

The 273 Commando in my 66 burned a quart every 100 miles, when I pulled it apart, the only thing that looked bad was the valve guides and valve seals. Ran real good. I've run knurled guides on small blocks that ran 300K before they got loose. Blowby sounds like rings are not sealing. If the "rebuild" was a rering, bearings, and a valve job it would make sense. I like 273's, they have a lot of heavy duty parts from the factory and were very efficient. On the other hand, it is nice take your time rebuilding a spare engine and swap them in a weekend...