Its a custom job for sure.
The W57 behind my 1G-GZE in my RA23 used two orginal holes of the 4 total on the g/box cross member.
I had 2 pieces of 3mm steel welded on each side of the old W50 bracket and two new holes cut. I also had a 3mm plate welded inside the bracket to lift the g/box back up by this amount; as the 3mm steel mounting bracket 'extensions' lowered it by that amount and I was keen to keep the angle to the driveshaft yoke the same as the factory tolerance.
If this does not make any sense, PM me with your mobile phone number and I will call you and explain it further.
Cheers,
Mitch.