Hey Steve, That picture looks familiar. :
The upper one is from a 1967 Barracuda. Was that style used other years too?
The lower one is a repop.
Differences include:
the pick-up tube as everyone can see.
the float arm, which is obviously much shorter and pivots lower.
the resistance winding which is hard to see.
The original is exposed, the wire wrapped linearly on a dog biscuit shaped non conductive board. The copper arm is attached to the pivot.
The repop resistance winding and arm is enclosed.

The difficulties in making a good repop or fixing an original shouldn't be major. From my attempt at frankensteining its important to ensue the sheet metal seal doesn't get distorted. The other challenge is hunting down the resistance wire and making a little stamping fixture for the copper arm. Tere are probably folks who have been dealing with one off instrument repairs for really antique cars that have already been down this road.