I have grown fairly big acreages of oaten hay in Australia, and small acreages here in Portugal. I aim for 120 to 140 pounds per acre. I just did a bit of Googling on US sites because I thought your bushel weight was low. I note that 32lbs appears to be a US "standard". At the same time I saw quite a few references from current growers with bushel weights well in excess of 40 pounds, which is what I would expect, and at 40 pounds/bushel your 12 pecks should have given you 120lbs/acre. If it sowed 185 at that setting, then as Reyer Farms said "You should be good" at 8 pecks to give you 120lbs.
A bushel actually varies in size in different countries, but not by much and one and a quarter cubic feet is very close to the ones I know of. An Imperial bushel is 1.28 cu ft and the Winchester one is 1.24 (I think that is the measurement used in US, but not sure). There is another called the Avery, and perhaps more. If you want to check your bushel weight, make a box 12"x12" and 15" deep. That gives you the 1.25 cu ft which is close enough to the bushels I know of.
To complicate things still further for the farmer, the British grain industry still talks about bushel weights, yet measures the grain in kilograms per hectolitre, and a hectolitre is a great deal bigger than a bushel.