I will just start a list of things that people can get mixed up when doing engine swaps.
1 The motor looks like a 675 series ,that's 6.75 Gross Torque not a HP reading.
2 the original motor would be a 5 HP Briggs with a cast iron flywheel ,this engine would be an alloy flywheel. Needs cast iron Flywheel.
3 crank shaft must be the same size as the original motor.
4 Never start a biggs with an alloy flywheel without a blade plate or weight on the crankshaft as there is no mass to keep the motor spinning ,especially when starting as you get kick back.
5 You can install new rings but time wise and cost wise it's easier to buy a mower with a good engine for a engine swap.
6 Possibly cheaper to buy a working mulcher than what you will spend fixing a mulcher. I've seen them from $50 to $350 for a complete Rover 5 Hp mulcher.
