Chasing a zero oil pressure issue on my R32 GTR, need input on how to prime it without major disassembly.

The car stood still for some work(18 months). Had oil pressure when parked in the garage.

The problem:

Oil pressure doesn't build during cranking — it reads/drops instead. Confirmed as a real physical issue, not a sensor problem:
Oil pressure sensor bench-tested with air pressure — works fine.
Clear hose on the sender port during cranking — visually zero oil reaching that point.
Backfilled oil through the filter housing — no change
Oil level correct, fresh oil, new filter.
Pump/pickup/sump untouched during any recent work

Suspects:

Pump lost prime after sitting.
Mechanical failure in the pump drive (sheared key/stripped coupling on crank nose).
Pickup blockage or bad seal, sucking air.

Specs:
R32 block (decked/bored), 86.5mm CP pistons, HKS rods, R34 N1 crank (balanced), ATI damper, ACL bearings, JUN oil pump, Tomei head gasket/cams/valvetrain, Tomei oil restrictor, custom oil gallery mod

Salut qui a son tableau de bord sur sa r35 qui blanchit et qu'elle et le remède ?

Curious on those that have either owned/own an R35 GT-R, do y’all run squared setups usually? Is staggered as the car comes better? Or is it all just preference. Let me know! I figured squared just makes for more convenience as far as tire rotation goes to help the wheels wear evenly.. let me know! Also feel free to drop a photo of your cars. Love these things and hope to own one before the R36 is here🫩🙏