Stock life insurance companies of other States and foreign governments, in order to be licensed to do business in this Commonwealth, must have a paid up and safely invested capital, if a company of another State, or a deposit in the United States, if a company of a foreign government, of not less than the capital required herein for domestic stock life insurance companies. Mutual life insurance companies, organized under the laws of any other States of the United States, may be admitted to do business in this Commonwealth if they have the requisite funds of a mutual life insurance company, and, in the opinion of the Insurance Commissioner, are in sound financial condition, and have policies in force upon not less than five hundred lives, for an aggregate amount of not less than one million dollars. Any foreign stock or mutual life insurance company, licensed to transact business in this State at the time of the passage of this act, having less capital or assets than that required herein for domestic life insurance companies, may be relicensed so long as, in the opinion of the Insurance Commissioner, it is in a sound financial condition and otherwise complies with all requirements of law.