i've been looking for a rear end to replace my h145 once i get my turboed a12 running. i don't really want to change the PCD. i'm having trouble finding any H165\H190 in CA,USA. but i did find this https://losangeles.craigslist.org/wst/pts/5430924559.html
it is about 1" shorter then the H145 but i'm afraid of the 3.5 ratio being to high as i don't have any experience on this. this car is being built with the intention to drift so im sure the H145 wont hold up to hard turbo abuse.

H190 is common in CA, but they are usually 6-lug

The Falcon rear is the same PCD as Datsun (4-lug on 4.5 inch circle), so that's not a bad choice

3.5 will be slower acceleration. The A12 likes a 4.10 or 4.2 for best all-round street acceleration (and still return 80 mph top speed). On the other hand 3.5 will make for quiet and fuel-efficient highway cruising, and the turbo will give the A12 extra grunt to pull the tall gear. Just depends on how quick you want to accelerate

3.54 came behind A14 engines in Datsun B310, they were dog slow taking off, but they were fine on the road because you could shift down when you needed to accelerate