What year 235? The '53 and earlier ones with 2 acorn nuts often need some tinsmith work done to them before they will ever seal regardless of what you use. The later 235s need to be looked at too to make sure that they are not bent out of shape near the 4 bolt holes.
(Consider this a public service announcement for others if you have already made sure yours is straight.)

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission