The formula allocation for township and road districts for the distribution of motor fuel tax funds, provided for in Section 8 in the “Motor Fuel Tax Law”, may be used by the highway commissioner, subject to the conditions set out in Sections 6-301, 6-701.1 and 6-701.2 as respects the methods, equipment and materials appropriate for such maintenance or improvement, and, in township counties, with the approval of the board of town trustees, for the maintenance or improvement of nondedicated subdivision roads established prior to July 23, 1959. Any such road improved becomes, by operation of law, a part of the township and district road system providing such road meets standards as established by the county. In township counties, the board of town trustees shall condition its approval, as required by this Section, upon proportional matching contributions, whether in cash, kind, services or otherwise, by property owners in the subdivision where such a road is situated. No more than the amount of the increase in allocation attributable to this amendatory Act of 1979 and any subsequent amendatory Act plus 50% of such funds otherwise allocated under the formula as provided in Section 8 in the “Motor Fuel Tax Law” and subsequently approved as provided in this Section, may be expended on eligible nondedicated subdivision roads. Funds may also be derived from other road district sources, not to exceed the amount that would be allocated under the motor fuel tax fund formula.