What are the differences between a 25 and 35 horse Johnson(mid 80s) other than carburation? I own one of each but the 25 is in superior condition and was wondering if the block porting or possibly the exhaust tuner was different. It would be sweet and easy to simply swap carbs to make the 25 into a 35 but somehow that just seems to be too easy. Any insight into this would be much appreciated....Cmack