For what its worth I have a 1956 235" in my 49. The pump is long and the fan/radiator clearance is scary, possibly 3/16" at best. If I have to change a belt I am looking at a problem.
Having said that, the motor has been installed for over 10 years and (touch wood) so far so good. Make sure that your motor mounts are good. FYI I did replace my fan belt when I changed the seal in the timing cover, easy that way!
Bill


1949 Chevy 1/2-Ton
"Sedgewick"
In the Gallery
1989 Caprice