Given how little cost we are talking about I'd put 30W non-detergent in it (or 30W detergent - what ever is handy) but I'd only run it for 15-20 minutes to get it to operating temp and immediately drain it while its good and hot then put a quality 30W detergent oil in it and then run it the 5 hours and drain it again.
A guy I know that has been rebuilding engines for 30-40 years taught me that. He was also in charge of the new Cadet sales when the local IH dealer sold them. He would do the same with new engines and rebuilds. With a fresh engine/rebuild he'd run it up to operating temp and then drain the oil to make sure something wasn't wearing wrong (excessive metal in the oil). He'd then replace the oil and send it home with the owner with the instruction on the 5 hour break in. He knows half the owners never changed the oil at 5 hours. He always thought getting that metal out of the oil right away helped the engine last longer.
The first few minutes of run time will put most of the break in wear on the new parts meshing togather for the first time. After that you are splashing the metal and oil around in the engine for several hours. I'd also check the head bolts a few times in that first 5 hours too.