(a) No mortgage loan or investment therein upon any one parcel of real property shall exceed in amount at the time of acquisition:
(1) Eighty per cent of the fair value of the property if the property is a dwelling house primarily intended for occupancy by one family, and the loan is required to be amortized within not more than thirty years by payment of installments thereon, at regular intervals not less frequent than every three months; or
(2) Seventy-five per cent of the fair value of the property in all other cases.
(b) The extent to which a mortgage loan made under section 431:6-306(3) is guaranteed or insured by an agency of the United States, may be deducted before application of the limitations in subsection (a).