I've got prechambers from the factory in my 2010..... GEP 6.5L Diesel.
My understanding is the prechamber orifice size, shape, and orientation would need specifically designed for the combustion chamber it is mated to. All attempts I am aware of on the 6.5L engine to modify the prechamber orifices has led to worse performance.
The prechambers are usually made of exotic materials (e.g. inconel) so welding one on there may be more difficult than it sounds.