Are you sure its a forged crank...i looked up the part number you listed and this is what i found.....
CRANK SPECIFICATIONS:
Year CID Crank Material Rod Style Forging or Casting Number Stroke Main-Journal Diameter Rod-Journal Diameter
64-67 273 Forged Steel Light-duty 2128278 2128869 2205700 3.31 in. 2.50 in. 2.125 in.
68-69 273 Cast Iron Light-duty 2658278 2658393 3.31 in 2.50 in 2.125 in.
67-73 318 Cast Iron Light-duty 2658278 2658393 3.31 in 2.50 in 2.125 in.
74-80 318 Cast Iron Heavy-duty 2658278 2658393 3.31 in 2.50 in 2.125 in.
68-72 340 Forged Steel Heavy-duty 2532457 2843868 3.31 in 2.50 in 2.125 in.
73 340 Cast Iron* Heavy-duty 3462387 3.31 in 2.50 in 2.125 in.
71-80 360 Cast Iron** Heavy-duty 3418640 3418641 3418642 3.58 in. 2.81 in. 2.125 in.
*73 340 cast cranks are shot peened.
**74-75 360 4-barrel cranks are shot peened.
Important crank feature: Manual transmission cranks have pilot-bushing bores of 15/16 in. Smaller automatic-transmission pilot bores
will not accept manual-transmission pilot bushings.
Forged cranks can be identified by the 3/8-1 /2 in.-wide forging flash. Cast cranks can be identified by the 1 /4 in.-wide casting flash.
http://www.mopar1.us/Aengine.html