If it's smoking only on startup you might consider R&R the valve stem seals. A person could do an over the fender overhaul with a rering/bearing it which is dependant on how much out of round/taper the bores have & the amt of wear on the crank & pistons or it might be time (& faster) to change the eng but 1st I think I would do a compression & especially leakdown tests & find out EXACTLY how the patient is doing but from your description of the symptoms it does not sound good.