There's a French startup that does exactly that: https://www.phoenixmobility.co/en/ The company has generated a lot of press but the concept hasn't caught on in other countries so I assume it is not very practical.
It's not a turnkey sort of thing. Every 1981 F-150 is going to be a unique snowflake of rust, broken parts, etc..
There will be some amazing barn finds where you could pull the motor out and bolt in batteries and an electric motor on a weekend and then there will be trucks where you basically rebuild the entire truck from scratch.
What might be interesting is an electric rolling truck chassis production and then various vintage looking bodies you could attach to them.
I'm waiting for something like this IRL. Ford already sells chassis only trucks, so if they would just make that with the battery pack and motors, I could bolt on the body myself.
