I dont know, it seems u didn't have the luck I had. In my case I got my engine, then I got the harness, then the ecu, and then the resistor pack for the injectors. All seperate ppl, it can be done just alittle more headache. Front clips are always good, but its not necessary. I would suggest trying to get a complete engine set.
I also didn't change my clutch or my seals, or any gaskets except for my oilpan cause the delivery guy popped alittle hole in the oilpan and I HAD to take it off inorder to weld it. It was running like that with new belts, thermostat, waterpump for about 1 1/2yrs until I changed the timing belt again the other day and put new camseals. crank wasn't leaking, and one cam was leaking alittle. Timing belt was still good. changed the clutch last weekend with new rearmain seal, pilot bushing... OH yeah Im running right now with one of my altima fans not working, and temp is rock solid.
alot of parts u can get from napa in a couple days from the warehouse.
Its always good to keep some spare parts incase something breaks. Same as on any motor.
As far as the a/c goes im sorry to hear that its not working. I put mine in with my kaE compressor and charged it right up. Worked until I crashed my car. That idle valve and iacv are hard parts to find, I admit and its hard to find a ca in the junkyard, but if ur missing an sr ignitor, what are u gonna do. Order one, and until it comes in, the engine is a paperweight.
btw u can use an sr ignitor on a ca if u change the plugs. u can use a kaE afm, and compressor no probs. u can use a s14 sr ecu with a retune if u have too or a ca18de ecu with a retune out of a 87-89 pulsar nx se. u can use a sr flywheel/clutch assembly with different starter and shave the bellhouse down in one spot or a 85 200sx pressure plate (ca18et), ka clutch disk. Ka tranny if u put the ca bellhousing on it. ka driveshaft, ka trannymount/motor mounts(ca motor mounts are preferred) s14 sr intercooler piping, sr turboes(t2?), I think u can use a specific 300zx cam sensor, ka coolant sensor, ka radiator, ka shortshifter, 200sx alternator with bracket, 200sx waterpump, most low impedence topfeed denso style injectors(similar to KaE) or top feed high impedence if u iliminate the resistor pack... ohh family is here, gotta go.