So, a few months ago I rescued this PC3 motherboard from my school, and it wasn't in the very best shape (missing components and bent pins).

I managed to replace all the missing parts at that time, except for the BIOS ROM and another large IC, which I couldn't find. Therefore, it sat in a box in my attic, never hoping I could ever fix it ... until recently. I discovered the "revolutionary" idea of reusing 2MB ROMs from Pentium motherboards. Thankfully, there is a fan-made Atari website out there and I managed to get hold of the required PC3 BIOS file, then I flashed it with a Pentium motherboard (had to make a file containing the code 8 times to get 2MB).

I managed to get it running with an AT keyboard and an Arduino Uno (thanks to the info that I found here)
So far, I'm getting a 601 error (floppy disk fail), likely because one of the required chips is missing (the floppy drive light blinks for a brief second during POST and that's all it does). The required chip is a 34D441 and it's almost impossible to find a replacement nowadays. I tried using a common ISA UMC floppy controller, but it gives the same result.

Is it possible to somehow bypass the internal floppy controller so I can use a external floppy controller ?