well u need the brakes uprated get some 2.0 cav brakes, fuel pump, as yours is mechanical. Think you'll have to change all the fuel lines as there'll be to small umm you'll need wire it in to the loom (put extra bits in the fuse box)
umm dash display.
All the pump relays, the master cylinder will need changing as well. You might need structual strengthening as your metal work is thinner than gte. Someone else will probabley give you more advice. This is a rough guess of what you have to do. Why not get a gte instead be cheaper and less hassle there going quite cheap now, u cud pik one up for £700 good nic £400 will get u a rebuilt bottom end, good investment as theres lots of ragged ones out there. Your insurance will be more cos of the conversion as well
The 1.6 engine/box will bolt straight in. As the_pink_purse said, you'll need to uprate the brakes. The master cylinders were all the same though on Novas from August 88 on - coded "ED" - so if your Nova's newer than 88, no need to upgrade. Servos are 20mm bigger on the GTEs/diesels though, so worth using if you can get your hands on one - although not totally necessary.
There won't be any need to strengthen the shell, so long as it's fairly rust free. You'll need the fuel tank, along with the pump from a GTE/GSi. As for the fuel lines, some people use the ordinary plastic ones with injection conversions no trouble, but if it was me, I'd swop them for the steel ones to be on the safe side.
You'll have to join the GTE engine loom to your SR and also put the wires in for the fuel pump and pump relay.
Driveshafts are stronger on the GTEs, so if you can get them, then fit them. You can use your 1.3 shafts though, if you get stuck