Not sure if its the same part as the rubber sleeve for the plastic tanks, someone might know. But got a couple of of them that will fit the plastic fuel tanks knocking about your welcome to one, if it will fit.
The pump is the same, yes, but the metal tank uses a metal bayonet sort of fitting, and the plastic tank uses the flange (for want of a better description) that the cone shaped thing fits over. Two different methods for mounting the same thing. Don't think I have any pics of the metal tank type, but I seem to recall the haynes manual has a sketch.
What might be possible is to remove the bayonet style portion of the metal tank and weld in a flange to suit the later plastic type.