You can find some slightly more detailed specifications for the 550 here:
http://www.briggsandstratton.com/us/en/engines/other-engines/550series_other

It has a cast iron cylinder sleeve, and has a reported gross power output of 3.56 hp. On paper it is a decent engine, but you have to know its history in the field to form an opinion on its reliability and durability. You also have to see it, hear it, feel it and smell it before you know whether you would like to use it regularly. Its capacity, layout and concept are quite similar to the Honda GX120.

The side valve and OHV Briggs engines, and the Honda ones, are physically interchangeable (same mounting, same output shaft position) but all of them are produced with various options of output shaft diameter and length, so you have to look at this detail when selecting one.