Unfortunately, this appears to be a bug in New Vegas itself. I reached level 99, and the game crashed! What gives? While testing the mod, I did notice a couple possible problems, and I tried to find workarounds for them. The iMaxCharacterLevel standalone and one iLevelsPerPerk standalone (of your choice) will work together. These alternative versions can change the levels per perk to 1, 3, 4, or 5. Alternative versions which only change iLevelsPerPerk are available under optional files. These alternative version come in both level 255 and level 99.
Alternative versions which only change iMaxCharacterLevel are available under optional files. This mod may work with a mod that changes either of those, but you will need to test it for yourself. (GECK variables iMaxCharacterLevel and/or iLevelsPerPerk.) This mod is semi-incompatible with mods that modify either of the mentioned semi-variables. Save and reload your game any time you modify Project Nevada Mod Configuration Menu settings. Load this mod after Project Nevada in the load order. This mod is compatible with Project Nevada
I have only tested this with the Ultimate Edition, but it should be compatible with all (or no) DLC. Important Notes-This game should be compatible with any combination of DLC.