i have seen some trick sleeve jobs where they cut out the cylinder pretty heavy and insert a sleeve, i always go to red rooster for my stuff but i am sure other shops do it. i had a 400 once that ran tops, i let it go in the truck with the c6 and 9in for 150, i still cry about it, i was young 4 years ago and knew no better. a month ago i had a 351 w i might have parted with but i put that in my 79 and yanked the 351 c for my 55, if i come across anything i will let u know, even if it is a small block, u can find a cheap trans in the small block pattern, i have heads galore for a small block, i dont look to get rich off of. parts cars for those years should be plentiful?