A 235 actually runs a 53 or 54 main jet. I run a #57 in my 261 and it still is a bit on the rich side.
I pulled a BC off a '68 250 and it had a #63 main jet in it.
A lot of times the power piston hangs up in the Rochester B and makes it run too rich. Pull the air horn and make sure it rides in and out smoothly. You can polish the piston and bore to help.
