Porsche 356-based industrial engines were used for a variety of purposes,
including back up power generators, auxiliary power units (APUs), ski lift power
plants, fire pumps, and other industrial applications. Many have found there way
into cars. They must be modified for car use - as industrial engines, they don't
rev very high, have lower compression, less carburetion (single carb), magneto
instead of distributor, and other minor differences. These can easily be
changed, and because industrial applications were often under-worked and well
maintained, they make a great basis for a rebuild for use in a 356. Here are a
few examples (click for large photos):
A bunch of industrial power plants, ready for conversion!
An industrial installed in the bench for use in ski lift operation:

(Pictures courtesy of Myron Vernis)