There was not any kind of leaderboard for this era of F1 done for AC. Personally I think this suits pretty good. There's still a bug (that was in the original modern Leaderboards that I used as a base) in driver comparison. It doesn't pick up the correct driver from the grid and shows the gap to wrong drive name. I can easily fix that when I have more time.
Driver surnames completely visible. I used the colors to match the ones that were used in 2005 and 2007. The vertical authentic leaderboard for this era is possible to do but I think it would limit the visibility of the cockpit mode quite a bit. I also used Fruitger font that was used in 2005 and 2007. Font is inside the leaderboard package.
HOW TO INSTALL F1 2005/2007 LEADERBOARD:
1. Download the RAR package and extract the contents to /steamapps/common/ folder
so that the folder F1_05_07_Leaderboard goes to the ROOT of /steamapps/assettocorsa/apps/python folder.
2. Install the Frutinger Roman font that was used in the 2005/2007 seasons. There is that font folder in the Leaderboard package. Click the font so that Windows installs it automatically.
Make sure that the font goes also in /assettocorsa/content/fonts folder. It should if you extracted it properly.
2. Go to Content Manager - Content - Miscellanneous - Python Apps - And check F1_05_07_Leaderboard active. Make sure you deactivate any other leaderboards you have.
3. Now when you start the game in practice, move your mouse pointer to the right corner to click the icon that shows all apps. Click the desired 05_07 Leaderboard app visible (three of them and HALO hud) and move them to desired areas on the screen with keeping the left mouse button pressed. Press F9 to get rid of the AC default leaderboard display. That's it.
Video description has more information and has links to my 2005 and 2007 F1 Custom Championship seasons with all downloads.