I would use jacketed data but start low.
Somewhere before max you will find the most accurate one
assuming the bullet diameter matches the cylinder throats and bore.

The most accurate 44 mag load I have ever shot is 18-19 grains of 2400
(depending on which brand case is used) under a 260 grain WFNGC.
This is shot in a 7.5" Redhawk and is very close to the max listed for copper bullets.
The lead bullet has a little less friction in the barrel which lowers pressure some.
The gas check makes it all happy at higher pressure than lead alone will stand.
Some believe the LBT WFNGC bullet to be the ultimate hunting bullet.
Especially in big-bores (44 and up).

Loads for that bullet with 2400 seem to be scarce.
The Hornady manual lists as max 12.6 grains of 2400 with their 180 grain XTP
The Sierra manual lists 11.5 grains of 2400 as max under their 180 gr. FPJ Match.
An old Speer book lists 12.3 as max under a 180 FMJ.

The starting load is 10 grains. Go up a half grain at a time. I would not go above 12.
I'd bet your accuracy load will be right around 11 grains.

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Nemo