5/3/1 is probably your best bet unless you are going to hire a coach and get something totally customized. I don’t think that rep maxes are a good idea for someone who doesn’t have at least near perfect technique, and even then I would be cautious about using them regularly. What I would recommend is 5’s progression and 5x5 opposite first set last for squat and deadlift. You could also do OHP as the 2nd lift on the 2nd upper body day since you are actually training for PL, you could do close grip bench or just more benching for the first exercise.
Read through this thread:https://forums.t-nation.com/t/what-s-the-best-powerlifting-program-for-me/240611
I suggest you do the same thing. If you have questions then feel free to ask.