I just acquired a "Whitworth" sporter p17 in 30-06, but the only place on the rifle that says "Whitworth" is the buttpad. It resembles a BSA sporterized p17 I've seen earlier but it isn't marked on the receiver. It appears to be drilled and tapped at the time of sporterization and is stamped "made in england" on the right had side of the barrel just ahead of the receiver. It has two screw holes on the top of the receiver ring, and one just behind the charger area of the rear receiver. Any idea what one piece steel base would fit this? Thanks in advance.