Are all Briggs and Stratton push lawnmower engines interchangeable? I have a Craftsman from the '90s, 917.372.852, 5.5 HP, self propelled in good shape. I have access to an old Bolens, (the guy said just take it away if I want it) with a seized engine. Don't have the Bolens model number but it says plainly on the mower that it was a 4.5 HP. I would like to experiment around with a project using the Bolens mower driven by my Craftsman B&S engine. Can I do that?