Most t3-t4 turbos will bolt on. I had a 60-1 bolted up to mine. Which has a pretty large compressor housing on it. Also as for the external gate. That would require you to weld a flange off the manifold. More than likely a length of pipe ect to allow it to clear everything. I had a length of shedule 10 1.5" pipe cut and welded at angles to extend approx. 6" from the manifold, and end with the gate just in front of or behind the engine cross member I forget now...
As for the different ecu or injectors, well, that depends on the size of turbo, and how much boost you want to run. I would start with saying a smaller t3t4 turbo shouldn't need anything. The larger you go, the more "tweaking" you should do. I would recomend runing 3-4psi more than base pressure in your fuel pressure regulator, but then you lose some fuel economy. Another alternative is to lighten the spring in your maf, of to which this is a very delicate mod that you want to do slowly, don't just loosen it alot, only a tiny bit will have a big effect! but the same thing happens, a little worse fuel economy, and also that wouldn't raise the saftey threshold as the raising fuel pressure would. Both fixes would be bandaids, and shouldn't be performed without a wideband. But if they are do so slowly, do some runs, and read your plugs, don't just go run hard thinking your fine...