A lower FOV actually translates to better PPD. You can use a basic formula: sqrt(hRes^2+vRes^2)/FOV. So a 100 degree FOV would give you about 36PPD, but a 90 degree FOV would actually give you an even better 40PPD. 60PPD is Apple's target for a "Retina" display, although there's a strong argument that you need double that at least for line pairs. For computer work purposes, we really should only care about matching PPD of a monitor. 36PPD is about equivalent of a 27" FHD monitor from 2ft/60cm: https://qasimk.io/screen-ppd/ and is probably good enough to start on focusing on other aspects of your optical design.

For a bit more nuance, here's a nice article that talks about how rendering geometry maps to FOV https://risa2000.github.io/vrdocs/docs/hmd_fov_calculation.h... although notably this does not account for the distortion shaders used in modern HMD pipelines to correct both for geometry and chromatic aberrations. There can be more techniques for improved text rendering, like what Oculus does with their timewarp layers: https://www.facebook.com/permalink.php?story_fbid=1942692682...

For those interested, here's some discussion focused on optimal text rendering in 3D engines: https://bgolus.medium.com/sharper-mipmapping-using-shader-ba...

In a previous thread, @kanetw was actually kind enough to chat in more detail about some of the Simula's optical specs: https://news.ycombinator.com/item?id=29930547

For some basic references of different aspects of visual fidelity for HMDs, this old writeup by UC Davis professor/VR researcher Oliver Kreylos is a good place to start: http://doc-ok.org/?p=1414

If you're interested you can surf through his blog for lots of insights. Also, this doc is one I just found that does a good job covering a bunch of the optical issues with HMDs: http://almalence.com/doc/SPIE-11765-23-V3/Near-eye_display_o...