Yes, peak HP in a typical gas engine is almost always at a higher RPM than peak torque, but the difference in HP at the given RPM's seems a bit high. In other words, what I'm getting at is that claimed HP rating on those gas engines seems a bit...optimistic.
In the case of the diesel, they give the peak torque at 3,000 RPM (94 lb-ft). At peak torque that's 53 HP, a fair bit over the peak rated HP. That doesn't make sense. I have never seen an engine that puts out 1.5 times the peak HP rating...they would have labelled it as a 53HP engine.
Diesel peak torque RPM varies a lot depending on the displacement (smaller diesels typically will run at higher RPM than large displacement ones). The 5.9L Cummins in my Ram 2500 puts out peak torque at 1600 RPM, and engine RPM redline is 2200 RPM. Large diesels, like those in an 18-wheeler typically make peak torque around 1100 RPM with an RPM redline around 1500 RPM. Diesels are RPM limited by design, due to the pressures, thus they make up for the lack of RPM with massive torque output. In the end though all that torque gets traded back to RPM in the drive train in order to spin the wheels at usable speeds.
I dunno, it appears to me some small engine makers are making some pretty inflated claims, and at least one diesel maker isn't making any sense....at least mathematically.