Based on your information, to meet the HAZ hardness requirement of 200BHN, you will need to PWHT the weld coupon. The affect of PWHT on impact properties is usually beneficial, meaning that you should be able to achieve the impact requirements at -45 deg F. The PWHT will have some affect on the tensile strength of the weld metal, so be aware. With a maximum hardness requirement of 200 BHN, you should be ok.