@ bd139: Thanks! I may place an order from JCLPCB for some 7K adapters in anticipation of the need to change some caps in my 7854. The ones I got from OSHPARK are A+ quality, so I'd like to compare them, anyway.
@ Daniel: OD of the cap can be no more than 30mm. Even that is a squeeze, so I would go 28mm or less diameter. Obviously, you'll never find longer caps than the OEM, so any length will do.
The manual states 5000uf -0%/+100% 25V (C1552) and 5500uf -10%/+100% 30V (C1542), so I chose 5600uF to replace both the 5000uF and 5500uF, which worked fine for me. I tend to aim for slightly higher voltage rated caps, so I originally chose the following 63V rated, which are 30mm diameter and barely fit:
https://www.mouser.com/ProductDetail/871-B41252A8568M000The ones I posted
above previously seem ideal for replacing either, and are 5600uF 35V and 25.4mm diameter. Just purchase ones that aren't stated in the datasheet to be "low ESR". You also want ones that are designed for SMPS or line filtering, which you'll be able to tell easily by the stated "test frequency" on the datasheet. If you click the link and scroll down, you'll notice that it states "Test Frequency: 120Hz". Another indicator for this is that the datasheet will state under "Applications" that they are for ideal for power supplies.
If you want to be quick about it, you could just solder some insulated wires to the capacitor terminals (with some heat shrink tubing over the exposed conductor), feed those through their respective holes, and then bridge the 3 ground holes together with more wire. The original caps are metal cans, so all three of the grounding holes are connected in the original design. You could just zip-tie the new cap to one of the original ones if you so choose, and it will work fine. Myself, I prefer to have the new cap firmly attached to the main board, though.