The Campbell props have a very good reputation. On our 1984 E30+ with the larger 5416/M20 engine we have a
13 x 9 inch 2 blade folding prop, and the company said it should be 15 x 9, though we don't have enough clearance for that.
So the prop you're considering sounds a bit small to me, though maybe that's the difference between a 2 blade and a 3 blade. But if you're checking with the experts, they will know best.
Frank