Firstly, congrats on your meticulous restoration work - wonderful job.
Funhouse is such a fantastic game when it is fully functional - your efforts will be well rewarded.
Thanks heaps for posting the speaker info site . . . I've been planning to upgrade the bass speakers in all my collection at some stage, but felt a bit uncertain about the technical implications.
I did replace the bass speaker in my CFTBL with an 8 Ohm 8" Jaycar subwoofer some time ago. The original 6" speaker and grille had been stabbed several times from below. At the time no 6" 8 Ohm was available, but luckily I had the sense to match the impedance. The sound is much richer and "boomier" which I reckon is desirable on this game with so much music.
I guess you looked at those el neato speaker kits from the US but their prices plus freight are way too much.
Once again - well done! And great pics too