Try and find original analog (potentiometer based) pedals. Short of that, make your own or use PC ones hacked into a gamepad or .
If this is going in the same cab, you can just use the G29 ones.
Analog pedals are needed for a few important games like Pole Position. It's pretty much unplayable without an analog gas pedal.
Stay away from the ones that just use an on/off microswitch.
The best hi/lo shifter is an original one. These stay in place unlike the up/down sequential shifters on modern games.
To save money they only put one switch in them. If you weren't in hi, then the game would default to low.
Problem is that there was no consistency as to which side they put the switch on. So you'll have to add a second switch or use the NC tab on the switch that is there.
Using the NC tab will work, but that button will always register as being pressed so you'll also have to add a bypass to turn it off while mapping other controls.
MAME also had to be configured in a specific way to work with the original shifter. The default is to treat it as a toggle that's activated and deactivated by pressing the same button.
See the driving cab info thread stickied at the top of this forum. If you weren't worried about the full experience, you could just have a shift button and use MAME as is.
I'd also recommend an original wheel. They usually aren't that expensive used and are built to survive abuse. Make sure it comes with the optical boards and then interface it with the PC using an Opti-Pac.
Opti-Wiz is another option, but it only works with "active-low" controls. Most original controls are active low, but if you end up with one of the oddballs that was active high, the Opti-Pac can be configured to work with that as well.
I haven't kept up with new devices being offered. IIRC, Ultimarc might have a device that can be configured to handle both the optical steering wheel and analog pedals.
Do a search on the forums as to what active high and active low mean....or maybe PL1 will take the time to explain.