as already mentioned the os 91 is a better solution. the ramtec was designed with that motor in mind so backing down on power may not be the best solution. If you can still find one, a k&b 82 was a decent motor and in a dynamax fan would give respectable performance, while being rather fuel efficient. pipes and parts might be hard to come by for this motor these days.

if applicable let your inlet size determine the fan you need. someone may correct me but I seem to remember 17 sq. inches is the threshold for using a ramtec over a dynamax. if you are over go ramtec, under go dynamax.

You would want to consider all this in your selection. Also check the RCU classifieds, there are NIB components over there at a fraction of the mfgr pricing.