5/16 HT chain will accept a 7/16 Crosby shackle. The G-209A has a WLL limit of 2 2/3 metric tons (vs 1.5 for the 7/16 Crosby Red Pin)

Here is a chart with the dimensions and WLL of the Crosby G-209A shackles:

http://www.defender.com/pdf/002082.pdf

edit, and yes by all means bow on the anchor side, to allow for movement, and pin through the chain