ST. LOUIS — Attorneys pushing for a judge to give preliminary approval to a proposed $75 million settlement of a class-action lawsuit against the NCAA said Friday that claims it unfairly forces athletes affected by head injuries to forfeit hundreds of millions of dollars are untrue. In a Chicago federal court filing that's part of what's likely to be a long approval process about the deal, the attorneys countered opposition lodged last month on behalf of Anthony Nichols, who says he sustained concussions while an offensive lineman for San Diego State from 1989 to 1992. Nichols, who would be among tens of thousands of male and female athletes covered by the sweeping deal, has argued in court documents that the proposal's benefits to athletes would be paltry compared to what the NCAA gains: legal protection from having to pay out what the filing argues could have been a billion dollars or more in damages.