Engaging in the activities authorized by ORS § 731.380 by a foreign or alien insurer shall not subject the foreign or alien insurer to any tax, license fee or charge, except as provided in ORS § 731.380, for the privilege of doing business within the State of Oregon or to any tax measured by net or gross income. However, if the foreign or alien insurer acquires any property given as security for such a mortgage or trust deed, all income accruing to the foreign or alien insurer solely from the ownership, sale or other disposal of such property is subject to taxation in the same manner and on the same basis as income of corporations doing business in this state. [1987 c.94 § 119]