Congratulations on coming back so well from your surgery. It sounds like you have done a very good job of it so far. I hope that you are out of the woods with the injury. I think the PPA is well within your abilities because it has much less impact than normal mountain races. Jumping right to a 100k race however MAY be too big of step. I always want me athletes to err on the conservative side and avoid potential injury. As you know too well, nothing will derail your dreams faster or for longer than a running injury. It does sound like your training volume would support the 100k effort were it not for the injury history and lay off it forced. My recommendation would be to start with a shorter race to more fully assess your readiness.