Not sure about the MC30s, but for the MC60s I bought a drop-in which had only two sections instead of 4, but they were larger in capacitance; used them to add a little to the power supply. One of the sections was dedicated to power the C8 preamp, and I never will need that ability, so I left it out. That left me one section short, and I fabbed a bracket to hold a modern axial electrolytic under the chassis.
The cosmetics of the replaced cap is perfect, the amp performs even better, and it looks neat underneath. Cheaper than Authenticap.
But if you aren't reasonably confident with tweaking a circuit slightly and safely, Authenticaps are the way to go. I don't think re-stuffing is a really viable option, and simply disconnecting the originals could set you up for a messy leak later on.