Hi,
fortunately (because I'm an oldie) I've had a lot of experience with Wisconsin, Onan and Deutz engines in a variety of applications. In the correct application they were/are all bulletproof!
Always use a suitable viscosity HD lubricant, keep oil and air filters up to scratch, keep the air flow unobstructed/fins clean and the drive belts (where needed) in good order
Here's one to consider - a Zaporozhets - Russian air cooled V4 in a rear engined car the size of a VW - from the 1950-1960s. And of course we have the Tatra V8s