I was just reviewing your original post, you said the engine had a noisy lifter? Have you had a chance to address that issue yet with all your efforts? One other thing you might consider before you fire it back up again is check the compression.
You also mentioned synthetic oil previously. There are a lot of opinions on the subject, some highly charged. What I've heard and it sounds logical to me, is that oil, conventional and synthetic, never looses it's viscosity but it does become dirty.
Thus, I try to continue the habit of having the oil and filter changed every 3,000 miles. I use conventional on mine. (I clocked 335,000 miles on a 1988 Mustang 5.0) If the engine has over 100,000 miles I would consider using a higher weight like 20/50.
Anyway, good luck with the rest of this. Looking forward to hearing good news when you're finished. I hope your son appreciates your efforts!