[Special Coupe Frank]

If the engine doesn't foul plugs or spew a constant cloud of smoke, and the oil consumption is "reasonable" (not more than 1 qt in 300-500 miles), then I think I would leave it alone and keep an eye on the oil level.

A few puffs on shifting is nothing to be ashamed of with a 90 year-old car.

Watch some silent movies with cars in them, you'll be surprised out how much smoke some them spewed when they were less than 30 years old...