I used the 235 oil pan on my 261 & used a 235 gasket. I have never noticed any difference in the gaskets. However, unless you either intend to do some work requiring the removal of the oil pan or the current one is leaking (if there is a leak it probably is the rear seal - not the gasket), I would leave the old one alone. While this is not a difficult job, it is fairly tedoius and somewhat akward with the engine in the vehicle. Also, it needs to be done correctly, and that just takes a little time. That's my experience anyway.
