OK, now I see the picture. Common practice here, as I was taught by the 'old timers' and to be code compliant:

Splice the neutrals 'thru' to eliminate the screwshell.
Install 'S' fuses and adaptors, sized to the AWG of the branch circuits.

That said, we used to replace the old fuse boxes with either two or four circuit panels, and eliminated the fuses altogether.

Along the same lines, on HVAC replacement jobs, occasionally I see 60 amp fuses in the disco, and the proper CB in the panel to match the MOCP of the new compressor. (Disconnect & feeder not changed)





John