Classic/Antique Car Repair: Small block smoking, wt oil, valve seals

Question
My 350 Chev. engine smokes all the time. I bought it with 35K since overhaul. It runs perfect. It sat for 3 years before I got. It has good oil pressure at idle. Could this possibly be oil seals? Any sure way to tell? I installed this in a '38 Ford. Will synthetic oil smoke as much? I'd hate to tear it down being that it runs so good.
Any ideas would be appreciated.
                           Thanks

Answer
HI;
   It has 35,000 miles on it ? that is not that bad.But if it sat for 3 yrs I think you might have some gaskets leaking on it.As far as synthetic oil I do not use it I stick with the regular H.D. 10 w 40 or a 30 wt. or 40 wt oil. I would get some spray GUNK and spray the engine off real good and try to see where there are any leaks also tighten up all nuts, etc. valve covers and check for leaks, you might need valve seals? and if it is smoking out the ex. pipe you should try a hotter plug. and see if the carb. can be adj.