Developer Steel Equities has modernized other former Grumman plants in Bethpage, some with county aid.
Steel Equities executives Joseph Lostritto Jr. and brother Glenn said they have similar plans for 1 and 15 Grumman Road West, which include a 372,000-square-foot building and land suitable for another building.
The renovations, expected to cost $3 million, include a new roof, facade and heating and cooling systems.
"We don't have any tenants yet . . . but we certainly hope the changes we are planning will make the building attractive," Joseph Lostritto Jr. told the county's industrial development agency last week.
Steel Equities, based in Bethpage, will use its own money to buy the property, which is selling for $7 million.
The IDA agreed to freeze property taxes for five years in return for Steel Equities' promise to find tenants that together would employ 340 people. The developer also received a $259,000 sales tax exemption on materials needed to renovate the building.
If the goals are met, Steel Equities would be eligible for more property tax breaks over 15 years.
Nassau County Executive Edward Mangano said the aid "paves the way for redevelopment of one of the largest available industrial parcels remaining" in the county. It has languished for years under a string of owners.
The IDA last week also supported a proposed 72,500-square-foot office and warehouse in Port Washington for Ivy Enterprises, a subsidiary of beauty-care supplier Kiss Products Inc., also of Port Washington.
The $13.5-million project at 3 Seaview Blvd., is located near Kiss' other buildings, which also received IDA assistance. Kiss sells do-it-yourself nail kits, eyelashes and cosmetics.
Ivy expects to add 30 to its workforce of 80 in the next three years.
Jin Kim, product management director, said the company considered moving to the Midwest or South but is staying. Nassau has offered Ivy a 12-year break on property taxes, $105,000 off the mortgage recording tax and a $583,000 sales tax exemption on equipment for the new facility.