OC703 would work. Other similar options would be OC705 and 8lb mineral board both of which would have higher absorbancy ratios due to being more dense. I checked SPI's website and the closest location to you is in San Fransico which is a bit of a drive. You could always do what I recommended to another member which was call any and all local insulation sales/installation areas and see if they will sell you any of the materials to you.
If you find a local place to sell it to you the end result will be far less expensive costing about $35 for an equivalent amount of mineral board or about $100 for the same amount of OC705.
