UNC Resources Inc. of Falls Church has offered to pay $22 a share in cash and stock to take over Texas International Co. of Oklahoma.

UNC said it is willing to give $107.8 million in cash for up to 49 percent of Texas International's stock and will swap stock for the remaining shares.

Texas International Chairman George Platt responded that the UNC offer is "well below management's assessment of the value of the company."

Details of UNC's offer were disclosed last week, after an announcement by Texas International that UNC was making a bid for the company.

UNC Resources is the parent of United Nuclear Corp., which mines coal and uranium, processes nuclear fuel and services atomic plants. Texas International is in the oil and gas drilling and equipment business.

Accepting the UNC offer would require Texas International to drop its plan to merge with NFC, another Oklahoma City energy company, Platt noted.

In trading on the New York Stock Exchange last week, Texas International and UNC shares both gained from the $16-$17 range. Last May, Texas International rejected an $18-a-share offer from Gold Crown Corp.

UNC said the combination of cash and stock it is offering for Texas International is meant to make the takeover a tax-free transaction for stockholders who choose stock instead of cash.

Under the offer, each share of Texas International would be traded for .44 of a share of a new issue of UNC preferred stock, paying a $2.50-per-year dividend with a stated value of $25 a share plus .44 of a share of a new issue of convertible preferred stock, paying a $2.125 dividend. UNC said the stock could be converted into shares of UNC common stock at a price 15 per cent above the common stock's trading price.

Texas International's Platt questioned whether the stock offered by UNC would be worth the $25 a share claimed by the Virginia company. He said his firm would respond to the offer by Thursday, the deadline set by UNC.