I am an electrician so it is usually simple and safe for me to install longer wires from the meter socket if necessary. The cost of a couple feet of wire isn't too much.
A lot of times there is enough play to stretch the wires in place.
make a top install version of this breaker.
Hopefully the bus isn't burned badly behind the breaker. You won't know until you pull it. Be careful not to do any more damage while pulling it out. It may be a bit welded to the bus.
PS. The Home Depot used to sell this breaker for $100