I have owned a 100HP STOL C150 for 25 years, so I know what they're like. I have considerable experience flying 150HP 150's on wheels, floats and skis. The only really good reason to increase the power of a 150 is for use on floats or skis. You lose utility in the tradeoff.
My Teal amphibian was changed from 150HP to 180HP by it's former owner. It gets airborne better, but that's all. everything else is about the same except furl burn. Definitely not worth the cost to modify.
235HP would result in a 150 which had very poor utility, and demanded great pilot skill. Sell the L540, and buy a stock C150.