Ok so far so good. I have the 455 mounted and in place. I had to use the old 389 engine mounts and modify them just a bit. So far it sits in there well, I hope to attach the tranny up this weekend and see if it all goes without a hitch.
Only thing so far is the crank pulley from the 455 wont work as its hitting the bonny cross member. So I will either find a smaller crank pulley or chop some of the cross member.
More updates to follow.