All of the normal 12V stuff should still work - especially on older cars. Speedo should work (assuming you are keeping the transmission) - a tachometer will require some tricks though (as there probably is a hall-effect gear that was part of the ICE engine).
Fuel gauge, temperature gauge and check engine light can all be made to work, but need to be customized for your controller, BMS system etc...
Power steering and power brakes must be re-worked - lots of options and information on this site.
Also you have to think through how to get heat (essential) and A/C working (if required).
Best to do lots of reading on what others have tried, then make up your mind about what fits your car and your budget...
Fuel gauge, temperature gauge and check engine light can all be made to work, but need to be customized for your controller, BMS system etc...
Power steering and power brakes must be re-worked - lots of options and information on this site.
Also you have to think through how to get heat (essential) and A/C working (if required).
Best to do lots of reading on what others have tried, then make up your mind about what fits your car and your budget...