CHICAGO (STNG) - After hiring engineers to determine the cost of renovating 94-year-old Wrigley Field, the Illinois Sports Facilities Authority will make an offer to the Tribune Co. next week to buy the historic ballpark, a top official said Monday.

Former Gov. James Thompson -- now the head of the stadium authority -- said he won’t know how much money is available to buy the stadium from Tribune Co. CEO Sam Zell until he knows how much it would cost to modernize Wrigley.

“I need enough money to credibly restore it to keep the character and give the new owner enough money to compete,” Thompson said. “If we can get enough money to meet those two goals, great. If not, I don’t want it. Why would I want the state to take Wrigley Field and not restore it?

“We’re still looking at the field to see how much restoration would cost. With that in mind, we’re going to prepare an offer to the Trib.”

Zell’s plan to sell naming right to Wrigley to generate as much as $400 million over 20 years -- in part to renovate the stadium -- has met with stiff resistance from baseball purists and die-hard Cub fans.

Thompson once again predicted that a naming rights deal would not be nearly so lucrative because there would be a strong push to keep the name Wrigley Field attached to the new corporate moniker.

“It’s probably going to be Wrigley Field at XYZ Plaza. What that’s worth as opposed to straight naming rights deal, I have no idea,” the chairman said.

What happens if fan opposition kills the naming rights idea?

“Every dollar that is not in the deal is a dollar that has to be subtracted from either the price paid to the Trib or the cost of the restoration. At the end of the day, you add up all the dollars and deduct what it costs to restore and run it. Whatever’s left over goes to the Trib,” he said.

Last week, Thompson disclosed that Zell’s plan to have the state acquire and renovate Wrigley would require the city to relax the ballpark’s landmark designation and to forfeit 30 years of sales tax growth generated by the renovation.

The proposal to relax the City Council’s decision to landmark Wrigley’s historic elements has also stirred controversy – among preservationists.

On Monday, the former governor stood his ground.

“The landmark ordinance has to be relaxed in certain aspects in order to allow new construction to make it a productive ballpark,” he said. “It doesn’t mean we’re going to rip away the things that identify that place as the iconic ballpark of America. They shouldn’t assume we’re going to gut the place and take away everything Wrigley Field has and all of its charm and ambience. That would be stupid.”

What happens if the Trib and the stadium authority cannot come to terms, or if the Wrigley renovation deal cannot be sold to the General Assembly, Mayor Daley and Wrigleyville residents?

As Thompson put it “If we don’t do that, somebody else will. It’s going to be sold to somebody and restored by somebody, so the Cubs will stay in Chicago -- which is why we started this whole thing.”