Speaking out of turn, perhaps, but I'd like to think that a (real) organ could be built to fill the space within that church without any need of electronic amplification.
If such a single, loud organ in one position, perhaps at the 'west' end (which of course is actually at the 'east' end!) proves insufficient, other installations in appropriate locations about the building - transepts?, chancel?, etc. - could, I am sure, do the job. Cost shouldn't be any problem, as the RC church is swimming in money!