1968 Baracuda

I just bought a 68 cuda today and will be starting a restoration after I get my garage built , I was wondering how hard it is to put a 440 in it , it has a 318 now , I know a 340 will bolt up but they are getting scarce with a low budget build . I had a 69 when I was 18 , 318 3 on the tree and will be 64 shortly , I guess I just don't buy that " you can never go back crap " it has an automatic on the floor and would also like to know if the console will support a 4 speed if I change it or if I have to add a piece to the tunnel, more to follow after i get a chance to look at it better , does have some rust holes under drivers door but not where anything bolts on , has some rust on bottoms of door and fenders but I don't know yet if there is any putty but with all the windows, chrome , bumpers and seats in place the 4500 price is pretty good price.