When looking for repower, do some reading on the engine series the unit you're considering came from. You want the biggest engine in the series because it will have the best power-to-weight ratio. For instance, my old OMC V4 crossflow 2 stroke is a 1.7 L powerhead and that engine configuration was used for everything from 75 hp to 140 hp, with changes in carb jet orifices being the only difference between them all. I love that my 140 hp weighs just 300 lb but I would suspect that the 75 horse from the same year would be a bit of a dog because it still weighs 300 lb. It also stands to reason that the bang for the buck is better on the larger engines in the range too; poor guy with the 75 hp paid for powerhead, leg and electricals engineered for up to double the horsepower he received. I don't know specifics on the more modern engines but I doubt that much has changed, it's still uneconomical for engine builders to have a different powerhead platform for each of the engine sizes in its lineup. Changes to EFI and engine management to give the right hp to match the decal and there you go. So you want a 135 or 150 hp that's the biggest of the 4 cyl lineup rather than the smallest of the 6 cyl series, you'll get more for the money.