dino 246 smoking

I have been enjoying driving my 246 gt since purchased five years ago. At the time of purchase it smoked alittle when warm accelerating from stand still. Now,25,000 miles later, it seems to do it more when accelerating from standing at temperature. Still has plenty of power. What are some likely problems that might cause this and solutions? The Engine was rebuilt 35,000 miles ago.

 

I would do a leakdown test first to give some idea of the condition of the rings and valves. If it smokes on decelleration it could be valve stem seals.