Just my $.02 worth, but if your happy with the oomph of your 235, don't go smaller with a 216. If you want a little more oomph, consider trying to find a 261, which is basically a bolt in replacement of your 235.
I frequently see 235's being offered for sale in various place in WA and the PNW. It would help with tracking down leads if you could be more specific about what part of the state you're in?
Your last question is better asked in the
Engine Shop forum, as it's more along the lines of technical information.
Best of luck in your engine search!
