Stockholders of M.S. Ginn and Company will get $11.26 a share -- about a dime more then previously expected -- if they accept the offer to buy out the company.

Ginn shareholders received notice of the improved offer yesterday, as the final step in the complex plan for a Pittsburgh conglomerate to take over the Washington office supply firm.

Shareholders approved the buy-out at Ginn's final stockholders meeting last week.

Under the plan, Ginn is selling its business for $8.9 million to MSG Acquiring Corporation, a privately owned company controlled by the Sidney Hillman family of Pittsburgh.

Effective last week, M. S. Ginn changed its name to MSG Investment Company, a holding company whose only business is to invest in tax-exempt government bonds.

Ginn shareholders now have a choice of accepting the $11.26 cash for their stock or keeping their shares in the new investment company.

The $11.26-a-share price is slightly more than previously estimated becauses the cost of completing the sale turned out to be less than expected, explained Marsh S. Marshall, Ginn's founder and chairman.

The buy-out originally was expected to give Ginn stockholders about $11.14 a share; that was later raised to $11.17.

Marshall, who owns a majority of Ginn's stock, is not selling his shares for cash. Instead he will take shares worth more than $4.5 million in the new investment company, which he will control.

According to the offer made to Ginn stockholders, the investment company intends to invest only in tax-free bonds and to pay all the interest it earns to its stockholders.