It's really seeming like 32 degrees of FOV is right on the edge of what's possible with the basic optical path I'm currently trying. Considering that I'm supposed to be aiming for 90PPD and not 80 anyway + the 2560px display is the highest available on the market, I'll try 30 degrees; a marginal difference that could make all the difference. This results in a PPD or around 85 which hopefully is the ideal compromise of feeling sharp and large at the same time. The 2160px would have a 25 degree FOV.

Unfortunately, the backlight for the 2160 panel is likely too dim for this application. I might have to see if it's possible to replace it with a more powerful LED, but that could add even more size to an already relatively large screen. Additionally, the display's contrast would be  even worse than the 800:1 already rated. Obviously, the biggest issue is the size, and 2 fresnel lenses in the system make for a rather blurry image it seems, so I'd have to distance the screen to avoid vignetting. I think the allure of a £20 screen might result in the project getting thrown under the bus or pushed back months. Oh, and the £83/each driver board really doesn't help. £200 for dim screens with sub-desired resolution and undesired size isn't exactly easy to swallow. The contrast is probably fine since there'd be a 40 or 50% passthrough of light anyway, reducing contrast even for OLED.

I have limited time and a lot of projects, so it seems that my simple yet inescapable choice is to use the 2560px screens going forward, likely pushing the BOM to the £1,000 and up club.