I've been searching the site for EASY disc brake upgrades for the REAR of my coupe. I don't want to have to weld anything. Drilling and grinding is OK. Is there anyone who has performed this type of upgrade? Especially to the back end?

series 2 bluebird discs/hubs can be exchanged onto a datsun 1200 ute diff. easier option may be to get a diff cut down and put in which has disc brakes already. ive seen lots of 1200 coupe race and street cars with this rear end setup (bluebird). im sure you can find a lot more info if you spend more time searching.

Yes Series 2 910 discs will fit. You can use them with your H145 axle housing also. Remove the bearing retainer and bearing from both H145 and H165 axles, swap disc brake backing plates onto your H145 axles and install new bearings and retainers. Check for a spacer on the H145(I think) which is to be reused. I had done this with my H145 - a bit of a hassle but can be done without too much drama if you are mechanically inclined. Bleed nipple may interfere with chassis rail on hard corners so you may have to scallop at that point. Anyway, keep searching on this site as more detail is likely to be found
Cheers