Buicks, Oldmobiles and Pontiac share a common bellhousing (commonly referred to as BOP bellhousing) and will not interchange with the 292 which shares it's bellhousing with the chevrolet small and big block V8's.
The 350 is by far the cheaper motor to warm up and put in your rig. I am building a 292 and if you look at it from a $/hp standpoint . . . the 350 is between 1/3 and 1/2 the cost, but not nearly as cool.
