Steve,
I used to have a 68 goat with a RAM AIR IV motor.
One of my all time favorite rides. Once lit up the tires in 4th gear (meant to used 2nd) furious smoke until the tires heated up and grabbed. Toasted my brand new clutch in an instant.
I would look at the possibility of a leaky intake gasket allowing water to be drawn into the intake. Have you been losing any coolant? Check the
oil also to see if any may have made it way into the pan. If it was that rich you would think it would run like crap all the time.
Best of luck and hope you get your roller soon,
Jim