[desertpat]

I think your valve stem seals are worn.
When you shut down the engine, oil in the top end runs down the valve stem past the seal and accumulates in the intake and exhaust, above the valves. The oil will drain into your cylinder if the valve is open. When you fire it up, a bunch of oil has already run down and accumulated - it burns all at once.
These seals are better replaced with the head removed but could be replaced with the head on.

To do this, remove the rocker assy. Work on the valves in 1 cylinder at at time with the piston of that cylinder at TDC (so the valve doesn't fall in the cylinder bore). You can use constant air pressure being fed in through the spark plug port to hold the valve closed (up) while you work on it.

Replace all the seal caps that are located under the valve springs and re-assemble the rocker arm.

I think you may have to buy a complete engine gasket kit to get the new seals for the valve stems.

Don't expect improved oil pressure, but there shouldn't be a puff of blue smoke on start up.

good luck