Well I would need to know what system you are interested in and if you have any special rules that need to be added. I’m currently working on adding the pathfinder 2 system, but still very early. I am not as versed with the system as Dnd.
The system is HARP (High Adventure Role Playing) and it's not related to D&D in any way. So this might not be something so easily tackled. In fact it has different stats than D&D and is basically a skill based system, even the spells are considered skills. The system is also point based as each level every character gets 50 development points to spend for stat increases, skills, and special abilities. Each skill has a progression rate and there are two different rates; favored (cost 1 per rank) and un-favored (cost 2 per rank). The progression rate is not as direct either. For the first 10 ranks in a skill the bonus is +5, then it's +2 per rank up to 20, then it's +1 per rank thereafter. I am working on a house rule that might change that though. Then each skill has two stats it gets the bonus from.... etc
The system is percentile based and the dice generally explode on a roll of 96 or higher.
So you can see this would not be an easy thing for you to do. If you wanted I could work on the stuff while you help me out here and there...lol.