Where could Loma be P4P, if he beats Shakur and Tank ?

It's hard to tell because the current 'big 3' look perfect - 2x undisputed, unbeaten etc. But beating Tank is a massive massive win, both sporting wise and marketing wise (these P4P lists are marketing really). Tank has perhaps one or 3 elite wins depending on how you define Pitbull Cruz & Ryan Garcia. The other win being of course Pedraza. Beating Martin, Barrios, LSC, Gamboa are not bad wins at all IMO, it's just that at his age, reputation and stage in career he should be fighting the very best only.
Shakur, regardless of how much your opinion of him was swayed by his last fight, is absolutely the real deal. Fighters (not near his weight class), trainers, promoters, analysts all pretty much agree he is elite. IMO he's the hardest fight for anyone at 130-140, so if Loma were to beat him as well he'd probably have the 2 most skilled scalps of any of the imaginary top 5 in this scenario. I don't think any of Inoue, Usyk or Bud have beaten a pair of fighters that skilled. I'd find it hard to not have him number one or two depending on what the rest do in that timeframe (they aren't getting a pair of wins that good in any case). With that said, I really don't see many routes to victory for him against Shakur right now. Shakur starts relatively fast unlike Loma, and doesn't really slow down significantly.