Univest Corp. of Pennsylvania said it will acquire Mount Airy-based startup Valley Green Bank, considered by many the top performing community bank in the region, for $76 million in stock. As part of the merger agreement, Valley Green shareholders will receive Univest stock equal to $27 for each share of Valley Green stock outstanding. That deal, scheduled to close in January, amounts to 2.25 times the March 31 book value of $12 per share. As part of the transaction, Souderton-based Univest gains…