Just my opinion, nothing more, but if the sale was not in the ordinary course of business, I cannot see why it would be reported as anything other than portfolio interest (Line 4, Schedule K).
A sale of an asset owned by the corporation (and previously used in the corporation's business) and then sold to a third party is not really a sale in the ordinary course of business (i.e., it is not inventory nor is the interest received on something like an account receivable).
