From looking at the photos, what makes anyone think it was overhauled? The cam looks like it may or may not be new, and a clean timing cover. Valve spring retainers look to maybe aluminum? If so, get rid of them. I am not knowledgeable about the rocker arms, but they didn't come on a 340, don't believe that they are TA's either. You can do what you want, no way I would even consider not going through it, NFW. It's not that much to go through it, except maybe the heads, or, something is really wrong with it. Maybe think about how or why ithe engine became available.
