Just replace the 2 roller bearings their oilseals and the conrod needle bearing plus spacers. I don't think that the crank goes as easy if you have the bearings with little movement or an unsmooth roll.
I change bearings every 150 to 160 hours if I don't get a shot crank bearing first. Every second to third time of crank bearing change (incl. conrod kit) I give it a new crank. So the crankshaft sees about 450 hours. About the same amount for a cylinder. 4 times piston change and 4 to 6 times replating and a new cylinder is most advisable.
Now the small bearings of the water pump and/or PV govenor are even more sensitive. A good brand somehow won't make it over 80 hours.
You'll need a flywheel puller and a case splitter, if you have access to a press, the crank bearing should be no problem. If not put your bearings into a freezer, better even on dry ice and heat the cases to about 150 degress celsius. drip some water on the case when it sizzles you are good. Work with gloves
That way those bearings should drop right in there.
Good luck
