A braze weld would be best. You would use typical exhaust pipe for the job. You could try flex axhaust but that might not handle the heat well. Regular exhaust pipe would be harder to work with for bending but it CAN be polished up pretty well, just takes some time. It could also be painted silver to closer match the mufflers.
A lot depends on where you can cut off the old mufflers.
The ride IS the adventure. The destination is just to get gas!