I have an LB conduit right above the meter panel on an overhead service. The power company said that the LB conduit needs to be "sealable" so that it cannot be tampered with. I need help finding the proper hardware to install and satisfy this inspector.

Rc,
The requirement for a "sealable" can be as easy as drilling a few small holes at the top and base of the condulet, for the POCO to install seals...
You need to ask them if this is an agreeable solution.
Otherwise, I'm not aware of a "sealable" condulet produced to satisfy the utilities...