The Pure has a completely standard bottom row, the only non-standard keycap is the 1.75x right shift and sets that have a Tsangan kit option will most often include a 1.75x shift, so a lot of Geekhack Group Buy sets will fit.
It doesn't have dedicated arrow keys, but the right hand modifiers can be toggled into arrows, so you can use it with them set to arrows permanently. I used it like that for a while, but decided I needed to use the right shift, so now I use the Fn layer arrows without a problem.
It's PCB mounted, but has a good solid PCB and mounts with 6 screws to the case with support ribs under the board, so doesn't feel as flexible as most other PCB mount boards.
The FC660M is a good option, also almost standard caps. The right shift is the same size as the left, so if you can organise an extra shift key and an extra bottom row key, you can fit any standard set to it. Plus you can get it with Clear switches
Both boards use Cherry stabs.