The Park Avenue blockfront between 54th and 55th streets is suddenly in play as the multiplier effect from the JPMorgan Chase tower redevelopment sinks in.

The co-op apartment house at 417 Park Ave. on the southwest corner of East 55th has hired Darcy Stacom and Bill Shanahan at CBRE to sell the building, sources said, and they could include the rest of the blockfront.

Joseph Moinian tried to buy it in the 2000s. More recently, Kushner Cos. offered $250 million before walking away.

The 1916-era, 13-story, 28-unit, co-op building could be twice as large under new Midtown East zoning — nearly 200,000 square feet.

The vacant retail store is represented by Robert Burton at Cushman & Wakefield, who is not privy to the board’s sales discussions but noted the area will change for the better when L&L Holdings’ new 425 Park Ave. across the street is completed.

Next door, the Stefano Ricci retail store at 407 Park could add 36,000 square feet to an adjacent project. It was purchased by an Italian company for $8.7 million in 2010. The selling points included the potential redevelopment of all or part of the blockfront.

The store’s lease is also up in April 2019 — just in time for developers.

“The entire block was always the play,” said Adelaide Polsnielli of Compass who represented the seller while with Marcus & Millichap.

To its south, the 19-story 1960s white office building at 405 Park Ave. was also the target of redevelopment.

In 2007, Steve Witkoff, Larry Gluck and a group of developers signed a contract, but the market fell and they lost a $41 million deposit after years of litigation. In 2016, it was sold to Deutsche Bank’s REEF and MRP Realty for $247.7 million.

According to Crain’s, they are now buying air rights from the adjacent men’s club, The Brook, to add four floors on top.

A redevelopment of the entire blockfront, however, could create a tall, modern, tower of roughly 500,000 square feet.

CBRE, the co-op board, REEF and MRP did not return requests for comment.