Just to add some info, I added the third download as the same as the second one with SCSI drivers but it is not exactly true because to install SCSI drivers, HardDisk SpeedTools had to move data to change partitions to add the one with drivers. So, because the data had been moved, if you try to use any tool to recover something from the past, you will not have the same result.
I will try to make one without touching data asap
About the problem with extensions, I think that the main problem is that the 7.7 installed on the partition is PowerPC optimized and so, at normal boot tries to load PowerPC code … and hangs.
I will try to make a fresh install on another "disk" on my BlueSCSI with a "universal" install (68k + PPC code)