There are some PSL stamped receiver blueprints / drawings around. The SVD has a milled receiver and the parts aren't available. Cold Steel solutions sells a PSL receiver blank with the lower bolt rails and I think it includes a template and the rear reinforcing / extension plates. If you don't have a factory one as a guide the instructions aren't great. The rear plates need to be thinned to half thickness where they overlap the receiver shell and the lower rails need fitting and shaping for the fire control group axis pin and their retainer. They are fairly beefed up compared to the factory ones and the type of steel is tougher.