In my opinion, it's a pretty close call, as to which one will be easier.
To put in the new JJ multi-section a.k.a. can cap, you will need to (1) take a picture of the bottom of the can cap wiring and other connections on your amp, for reference later as needed (2) drain the high-voltage DC from the old can cap sections (3) remove the current wiring and components from the old can cap (4) remove the old can cap from the chassis, which takes a bit of time and effort (easier if you have a higher-wattage soldering iron with a big chisel tip to heat up and twist out each of the can's tabs, but can be done regardless with metal nibblers, grinder on a Dremel, etc.) (5) install the clamp you bought for your new JJ can cap (6) install and carefully and correctly wire up the new JJ can cap.
To use the individual caps you bought in the kit, you will need to (1) take a picture of the bottom of the can cap wiring and other connections on your amp, for reference later as needed (2) drain the high-voltage DC from the old can cap sections (3) remove the current wiring and components from the old can cap (4) plan and implement a method to secure the new individual caps in place - like I said, I use terminal strips, bolted in place inside the chassis; others use hot glue or other goop (5) install and carefully and correctly wire up the new caps.
Up to you which way you want to go here.
While you are waiting for parts to arrive, there are a few things I'll point out now, that you'll want to come back to later.
The smallest cap from your kit, is marked Nichicon (that is the brand) and 47uf, 100v. My recommendation (more on this below) would be to use that one regardless of the choice you make above. The 47uF 100v cap was to be used as the cathode bypass capacitor for the power tubes, and is not part of the power supply filtering we have been talking about so far. But you might as well replace the old part that corresponds to this one too, while you are replacing the power supply filter capacitors housed in the can. We can come back to this later, but I'm just bringing it to your attention. If you go with my recommendation below, you'll want to use this small one, regardless.
Second, if you decide to use the JJ cap, note that it has four capacitor sections: 40uf, 20uf, 20uf, and 20uf, all at 500v, right? You need three high-voltage caps, with the original being specified as 40uf 450v, 30uf 350v, 15uf 350v. There is also a 50uf 25v cap specified on the schematic and parts list - that could be replaced with the Nichicon 47uf 100v mentioned above (from your kit).
So my recommendation would be to use your new JJ cap in the following way to best meet the need: wire up two of the 20uf sections in parallel. This will make your JJ cap have 40uf at 500v (to replace C52A, 40uf 450v on the schematic in the parts list), 20+20 = 40uf at 500v (to replace C52B, 30uf at 350v on the schematic in the parts list), and 20uf at 500v (to replace C52C, 15uf at 350v on the schematic in the parts list). This will meet or exceed all of the specs of the original power supply filter caps in the can. Finally, to replace C52D from the parts list, you can use that small Nichicon 47uf 100v, that came in your kit. That can be handled separately; we can come back to it later.
There are other ways to proceed, but this is my advice right now anyway.
