Nissan Repair: Replacement engine options for older car, datsun stanza, datsun 1200

Question
Hi, and thanks for your advice on my problem. I live in Australia and have an 82 Datsun Stanza Gl, which has an L16S-A engine. There is not too much wrong with it apart from a bit of a around the head, and it has only done 145000km. However, I am toying with the idea of replacing the engine with a more recent unit, one that can use unleaded (instead of premium plus an additive), one that doesn't depend on cold weather when starting (i.e., no distributor points!!), and one that has a bit more grunt.

So I have three basic questions:

1) I really have no idea where to start looking and what my options are. Which types of engines would be suitable to put into my car that would not cost the earth in terms of engine bay modifications?

2) It has a three spd auto trans., so also what amount of work and rough cost would go into converting it to a manual transmission?

3) If I did put a new engine and transmission in, do you think that I would run into issues relating to other parts of the system, such as steering, suspension, brakes, diff etc? I have seen people put SR20's into old datsun 1200's, but have no idea what sort of modifications this meant to the other parts of the car. I have kept the mechanics of the car in fairly good condition, but would an increase in power cause a lot of problems with stress on other parts?  

Thanks again for any advice you could offer.  

Answer
Lyle,

The SR20 is the answer but you need to get a complete doner car that runs because of the fabrication of mounts and such.  It will all fit fine but you will need the entire wiring harness and computer and an electric pump for the fuel to run the injectors.  The manual transmission would require you to find another car like yours to get the pedals out of and the hangers and master cylinder for the clutch and the hoses to feed the slave cylinder.  That is way it is important to get a doner car for all the late model parts and then find one of your year for those parts that are specific to your vehicle.  It can be done but you need to be patient with the wiring and connections for the new engine to go into the old car.  But, once you figure out the harness you will find that there is only a power, ground, switched ignition and the fuel pump circuit that has to connect up to your actual car.  All the rest plugs into the new engine and computer.