One last thing to check before condemning the engine - possible brake fluid seepage from the brake master cylinder causing fluid buildup in the power brake booster. Over time, if enough brake fluid accumulates, it's sucked through the brake booster vacuum line and burned. Lots of white smoke. I saw this happen on a friend's '71 BMW 2800 and my '67 Sunbeam Alpine. The guy who sold me the Alpine thought it had a blown head gasket.
Disconnect and plug the power brake booster vacuum source. See if the smoke goes away.

Happy Motoring, Mark

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DrDKW