Good points Dave - That 455 Olds is a full 4.5" wider, 3" longer and 4" taller than a 350. I think the starter is on the drivers side of the Olds too.

Would probably need a lot of sheet metal massaging as well as talcum powder and a big shoe horn!

But with enough desire, time, energy and some money - it could happen. But an LS1 sounds pretty good right now to me..