Hi there and welcome!
The Primary reason you are having trouble there is someone has Replaced the original Briggs and Stratton with a later Honda GX engine. The original Briggs is an upright engine and would not have stuck out so far toward the front.
I have seen a few of these with Honda's, though I have never paid much attention to how they were put on. I would reckon to make it work properly will require some modifications to the keeper to hold the belt away from the engine
