The hole isn't really that disastrous if they go cheap and live locally. I've seen pictures on this very site of set ups that would offend me more...
These are standard Frugelhorns with Alpair 7s. The XLs take the Alpair 11s or 10s.yes wouldnt use his home made horn bit but the rest is this i thinkÂ
https://www.kjfaudio.com/product/frugel-horn-xl-flat-pack-speaker-kit/#speaker-driver
https://www.hifiwigwam.com/forum/topic/125055-frugal-horn-xl-build/