I cannot imagine that 400 degrees would have done anything permanent to your bushings.
I have always had trouble getting those new bolts to go into those new bushings. I just put the half inch drive impact air wrench on it and drive it home and hope for the best. Never had any issues on three trucks. I suppose you could hone them to tight slip fit.
Carl


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