Reja confirmed on Tuesday that the Serie A side were nearing a move for the Portuguese international, who is expected to complete his transfer before Friday.
"We've been after Postiga for a week. He's got international experience and can play with [Miroslav] Klose," Reja told reporters at a press conference.
"We were about to finalise the deal [on Monday] night and I'll be particularly happy if Postiga arrives."
Postiga, 31, moved to Valencia from Real Zaragoza in the summer.