No, it is not a "direct" bolt in. The mount perches on the k frame will set the big block too far forward and twist the engine center line to the car. You could cut and move the perches on the kframe, look up Jim Lusk on here he has some how to videos ( in essence you are making a DC k frame ). Also the actual spool mounts are different from a small block to big block, so you'd have to source those and they are getting harder to find. The other option is the Schumacher conversion mounts (
http://www.engine-swaps.com/Pages/ProductsYear/73UP.html ) 73 up small to big block conversion.