Senate Finance Committee Chairman Bob Packwood (R-Ore.) yesterday named 11 Senate conferees to meet with their House counterparts starting Thursday to work out the final version of tax-overhaul legislation.

Packwood, who selected the panel's six Republicans, and ranking committee Democrat Russell B. Long (D-La.), who chose the five Democrats, broke the tradition of appointing conferees on the basis of seniority and selected two relatively junior senators on the Finance panel who worked for Packwood's tax-revision plan from the beginning.

Packwood named Sen. Malcolm Wallop (R-Wyo.), skipping Sen. John Heinz (R-Pa.); Long appointed Sen. Bill Bradley (D-N.J.) and bypassed Sens. Max Baucus (D-Mont.) and David L. Boren (D-Okla.). Bradley was one of the first legislators to push the idea of reducing tax rates and limiting deductions, as both the House and Senate measures would do.

Besides Packwood and Wallop, the Republican conferees are Sens. Robert J. Dole (Kan.), William V. Roth Jr. (Del.), John C. Danforth (Mo.) and John H. Chafee (R.I.). The Democratic senators on the conference committee are Long, Bradley, Spark Matsunaga (Hawaii), Lloyd Bentsen (Tex.) and Daniel Patrick Moynihan (N.Y.).

House Ways and Means Committee Chairman Dan Rostenkowski (D-Ill.) is expected to name his representatives to the conference committee today. Despite waves of rumors about who those conferees are, Rostenkowski aides said the chairman had wrestled for days with the difficulty of choosing loyal legislators without shattering the traditional of seniority. The choices are expected to include both senior members and ones who are especially loyal to the chairman.

When the conferees are proposed today, House Republicans are expected to offer a motion on the floor that would order House conferees to try to achieve low tax rates and doubled personal exemptions, similar to provisions in the Senate measure. The motion is considered unlikely to pass.

In the Senate, sources said that until an hour before the negotiators were announced yesterday afternoon, Packwood had planned to have five GOP and four Democratic conferees. Long chose Bradley over Moynihan even though Moynihan has served longer on the Finance Committee.

At the last minute, Packwood and Long decided to add Wallop and Moynihan. But in a parliamentary maneuver designed to weaken objections to the break with seniority, Packwood and Long named the two senators as an addition to the list of other conferees. Objections on the floor thus could only block the last two nominations.

"All conferees are equal," Moynihan said cheerfully after the announcement.

Meanwhile, Packwood said yesterday that the conference might agree to raise business taxes by $15 billion to $25 billion above the $100 billion, five-year increase in the Senate measure. The House bill would raise corporate taxes by $140 billion and give individuals a tax cut of equal size.

Rostenkowski and Packwood, who met in private yesterday afternoon, have endorsed the idea of setting individual tax rates as low as they are in the Senate bill, which has two rates: 15 percent and 27 percent. They also support cutting the taxes of middle-income Americans by as much as the House bill does rather than accepting the smaller cut in the Senate version.

"We're going to have to find $20 billion, $15 billion, $25 billion, and it's going to have to come from business," Packwood told a tax seminar.

House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) also weighed in yesterday with an appeal for more tax relief for middle-income taxpayers, saying he feared President Reagan and Treasury Secretary James A. Baker III are interested only in low tax rates and business tax advantages. "I hope the president restrains his own instincts to help the rich and his Treasury secretary's apparent determination to protect big business at the expense of the middle class," O'Neill said.