I can't say for certain that the manifolds are the same between the 194/230/250 and the 292 engines, although I think they are. Aftermarket manifolds and headers are usually listed as fitting all four sizes.
Engine mounts for the 292 are the same on the driver's side, but the passenger side engine mount is moved forward to the location of the smaller engines' fuel pump.
If you can't find a good 250, how are you going to find a 292? From what I've seen, the 250 is a lot more plentiful. It doesn't have to be from a truck, the car 250 is the same block. Check out Leo Santucci's "Chevrolet Inline Six-Cylinder Power Manual" and the
Inliners site for more info.
