Why not just use an alternative location to mount the same thing
If its a 1987 with the tbi, the switch part of that assembly is designed to provide an alternative ground to the fuel pump relay im pretty sure, which even chevy deleted in the 1990s probably realizing they had reliable enough computer grounding
Then the gauge on the dash can be run off the port by the distributor. leave the original alone if it wont budge. is the one by the oil filter using an adapter that comes out of the block that the switch/sensor screw into ?
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it looks something like this , right? show us what you meant if you still need to use this location
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This is an example of where the location im telling you to use is, its by the distributor toward the firewall on the little landing the distributor opening is at. that supports my gauge sender , and it can probably support the switch for the fuel pump too but it would probably take a second or so more cranking to get it to do its thing just because its higher in the oil feed circuit i presume