What was the last year for the slant?

That slant six can be made into a real powerhouse IF you don't try to do it using the tried-and-true, conventional methods of hot rodding.

A 300 HP boosted slant six would probably last forever (nominally) and is pretty easy to put together.

Food for thought...

I shortened the quote but I don't see anything wrong with it. The easiest way to make the slant breathe is to shove the air in with forced induction. It is complex and must be done correctly for it to live, but it doesn't come with the same trade offs as big cam, big carb, lumpy idle hot rodding does. What is max hp people are making with a slant somewhere in the 600 range. That is pretty good for an engine that started at a realistic 140 hp. I might be buying a tig welder this weekend and if I do I won't be able to stop myself from welding up a stainless turbo header.