lowest possible requirements to do barrows?

Depends on your gameplay experience / how good you are with game mechanisms. Find it out for yourself.

priest in peril i think

Literally could do it with ring of recoil and tic eating, so just access to morty.

Usually u at least want ibans staff and 61 range for rcb.
75 mage for trident and 75 range for BP is ideal though

I used void knight mace my first time before I had Ivan’s staff

Really not advised as it requires 2 blood runes per cast. Bloods are about 400gp ea. And only max a 20 which makes the spell in no way worth it.

Also before you try and say with charge it's a 30, you would have a trident at 75 so u wouldn't ne doing this at 80

Depends when his first time was. Barrows pre-dates trident by like a decade

Sure, but were are giving suggestions to op, not reminiscent memories of the old days.

https://m.youtube.com/watch?v=xdMmYM9RkyU

Level 4, but ideally having Iban blast at least and 43 prayer

im at 61 mage atm and 43 prayer!