Hi Hien Do, and a warm welcome to the forum. Its always nice to welcome another Rover 45 owner on board. I am sure our resident Briggs and Stratton guru grumpy will chime in here and give you the correct advice on the engine replacement. Once again, to Outdoorking.
Thank you, Deejay. First post, but has been reading the posts and watching the videos of this great site for months.