I had a very similar boat some years ago, mine was a Sears, but I believe it was built by Alumacraft. I ran a 1971 9.8hp Mercury on it for a bit, then a 1957 18hp Johnson, then we got stupid one weekend and stuck a 40hp Gale on it for fun. The fact that the hull survived is what amazed me most, besides the air born antics it enabled. (I was a lot younger and a lot dumber then.)
The layout was just three bench seats, and I ran a long fuel hose up to the bow to try and get some weight up there. Keep in mind that a 1959-60 Gale 40 is part of the Big Twin family and quite heavy, but it handled the weight okay. It was the transom flex that scared me. I came right home and cut two 3/4 plywood panels to fit the whole transom, one inside, one outside.
I only left that motor on the boat for a day or two, but it sure was fun in a scary sort of way. I took the motor off after I had to catch my old lady in mid flight as she went up, and stayed up and the boat started to pass under her. If I didn't put a hand up and grab her, she likely would have ended behind the boat in the water real quick. Seems to me that was the last time she went fishing with me too.
Still have the motor, but I sold the boat a long time ago. I seem to remember mine being a 1971 model according to the title but years and HIN numbers tend to get all screwed up here on boats before 1972 for some reason. I put the transom back to stock, hung a small electric trolling motor on it and stuck it back on its original trailer and let it go. The 16 year old 'kid' that bought it still has it, I see him and his kid in once in a while all these years later. I guess I didn't hurt it that bad back then.
In reality that old Gale was probably only making about 35 real hp, maybe even less but that was still 15 over the hull rating.
When I nailed the throttle, it would rear up and as the motor came up out of the water a bit on the hydrofoil, the boat would shoot forward with a vengeance. It was at that point when I realized my old lady wasn't moving with the boat but now air born and coming at me. She went up with the bow of the boat but the boat came down faster than she did propelled but the prop. She went up, then came down, but the boat shot forward. It was sort of a football catch. atop my right shoulder. I was glad she was tiny, around 92 lbs tops. I wasn't with her long, but I had the boat for about 5 years.
The set up was a rig, the motor had no tiller, it came off a small runabout and had a rope steer set up. I had rigged a short loop of rope and a lever on the right side that laid flat on the rear seat. to steer, and I used a mower throttle to accelerate. If the cover wasn't held on with rubber bungee straps like an old jeep hood, (factory set up), I'd have likely just strapped a paddle to the cover and steered it that way.