Firstly which H190 are you using because there were in order quite a number all different to a degree but all needing different setups because of that.

Firstly datsun 2000 Sports,Width OK 25 spline axles imperial fittings not metric.LSD available,Alloy diff centre carrier.

Next was the Datsun 1600 wagon similar to above but metric also 25 spline axles just like a 1200 Ute.
Width useable stock under a 120Y maybe 1200 with correct wheel offset ie Front wheel drive rims like a laser early model.

Next was the 620 ute diff width useable stock just like the 2000 sports,These along with the later 720 Ute diff ran large diameter tapered roller wheel bearings with shim adjustment and the axles used a thrust face inside the diff centre.
25 maybe 30 spline axles,Can't remember exactly and the ability to setup the axles with zero endfloat made them ideal for use with rear disks as they had zero pad knockback.
Used the Alloy centre like the 2000 sports.

720 ute 30 spline axles ideal candidate for a wider vehicle cast steel carrier bulletproof setup stronger than a nine inch ford in many ways.

Works PB210 diff based on a modified 1600 Wagon in a similar fashion to the 180b Panel vans used for the Stanza works cars(Late US 510 and 160J or Violet in different markets.

Next was the JDM 180 B Panel van which was an oddball with 28 spline axles,This was a lighter housing than the utes and was the basis used for the Works Stanza Diffs with the addition of baffles and internal reinforcing tubes fitted to the axle section of the housing.Initially used with alloy centre diff housing metric 180B panel van type.
Later upgraded to 720 type cast steel centre due to bearing issues with big powered engines.
These works type diffs ran custom 28 splie axles with double width bearings,Basically two 240K type inner front tapered wheel bearing races in a single outer housing with a double width bearing retaining sleeve,Later disk brake falcons and a few others used a similar wheel bearing type,These resemble some of the cartridge type bearings used in front wheel drives and the front of later commodores.Advantage being zero pad knockback.

The works setup had a machined carrier that fitted into the bearing section of the housing,Used a smaller OD bearing and half the bearing width was retained in this adapter section outside the actual diff housing,They included the caliper mountings and all ran vented top hat type disks of 260mm diameter.They will fit inside some thirteen inch rims as well.

There is also some variants in the Nissan Vans that can be adapted in a similar fashion to the 620 and 720 Ute models with the six stud ute type diffs using a five inch PCD on the studs you machine the outer section of the axle away leaving a clean centre section to drill for new studs in the standard Nissan datsun four stud pattern,Far better than cut and weld conversions as the Metallurgy of the axles is unchanged.

Finally we come to the two Bluebird variants in the wagons series two with 25 spline axles,Series three upgraded to thirty spline axles.
Width as to be expected and normal wheel bearings.The setuo with normal wheel bearings allows the axle to move in and out giving pad knockback and a soft pedal with two or four piston type calipers,This is the reason these types use a single piston floating caliper as they to an extent compensate for pad knockback.

So when converting to rear disks you need to either use a fancy wheel bearing setup,Yte type adjustable endfloat axles or floating calipers to alleviate pad knockback for good brake action and feel,No point having rear disks especially on a rally car if you have to pump the pedal to get brakes working.