IH #10 drill and Tall Fescue

Anyone have any suggestions for seeding tall fescue with the IH 10 drill, It has the small seed box on the front (alfalfa box)

and the large seed box behind it (oat box). I want to put down 12 lbs of alfalfa and 10 lbs of the tall fescue, I do not have the 8 tooth sprocket for the large box only the 16 tooth. Thinking I will need to mix oats with the fescue and run through the large box so it will flow? Anyone try running the fescue seed through the small seed box? I would seed them seperately if it would work better, or I am looking for the 8 tooth sprocket on e-bay now to run through large box without the oats.

Thanks for any ideas.

IH #10 drill and Tall Fescue