Mine is based on the presumption that the “other actor” will be spawned soon.
If the gauge is always spawned and the tank is sporadic then put the polling in the tank actor and have it poll the gauge.
Sounds like you are doing a vehicle modification system. Swapping out parts. If so I’d have a core component (Actor component) that all spawning in parts reference, then the AC would get/set data based on what contacted it. Versus having components like a gauge checking for a fuel tank or vice versa. That’s just me though.