Sheep. Sheep are good. 4 stroke engines that lose sump periodically last only as long as they last. How much slope do you have?

I'd say the hill is maybe a 25 degree slope. Not too bad but I wonder if a 4 stroke will not get lubrication on the hill.

That's a real good question. A four cycle that has the rotor style pump may not lose sump. But then again, is the full engine pressure lubed? Maybe it is better to start cheap!

Would it be too expensive to have the old LB completely rebuilt ??
Our American "flat rate" has gotten out of hand; as has environmental , security, and safety concerns.
We need balance..
By far the best suggestion is to use sheep.

I agree, keep your Lawnboy running. Probably a lot cheaper and better than anything new. The 10550 is a great mower. I see a lot of Lawnboys running 30 - 40 years old. Just make sure you rejet to eliminate the surge and to run cooler.

I think the possibility of a splash lubed engine losing lubrication from running on a hill is unlikely. There are lots of hilly lawns and the most prevalent engine is the good old flathead splash lube design. If the splash design did cause engines to run dry on hills mower repair shops would be littered with failed engines. This hasn't happened yet and we have been using powered mowers for a long time.