I have built something like this for my motorbike.
For speed and distance I use GPS (Neo 6) which seems to be accurate and more accurate that the mechanical speedo on the bike.
The thing I learned is that viewing contrast is important. OLED and LED are good for that. But you might think to incorporate a cowel to shade some of the sunlight. I haven't tried mono LCD but I would imagine that contrast might be a challenge and they are slower to respond. A colour TFT might be OK depending on the colours you display.
For another bike project, I used a simple serial 7-segment LED display which actually works very well, and so is worth considering (although less fancy than a screen).
You will need a solid way of converting to 5V or 3.3V. I use a switching step-down converter. Beware, the electrical environment is very "noisy".
I haven't tried to sense RPM. My bike is older with a cable RPM drive, so tapping that is not easy.
So I would be interested in how you are sensing RPM?
Hope this helps.