1500m = 4920ft elevation. The only way you can get one of these to run those speeds is by having it setup really loose. Here are my suggestions, and keep in mind that chances are you will NOT get 71 mph out of it, but if you want it to handle the way it should, you should shoot more for mid 60s max, especially at your elevation...maybe less.
First, take the wing off...we'll get back to it later.
Adjust your strut for about 1.25" depth setting it up flat on the table as described in the article. Set the turn fin so it is level with the running surface (table) this is a little tricky but you can get it close by setting a long ruler against the inside of the bend, parallel with the bend and adjusting the fin so the ruler is parallel to the table.
Set the steering so the rudder is straight at neutral setting.
Run the boat and adjust the fin and to get the boat to track straight with neutral rudder. Adjust the strut depth to get the boat to run tight without blowing over. This should be done in choppy conditions that closely simulate normal running conditions. Normally when the boat is setup tight enough, it will have a tendency to hop in smooth water, but will hold well in chop.
When you get these settings right, you should be able to take full speed (right hand) turns within a 35 ft radius (70 ft diameter) or so. Don't try to make it hold a 15 ft radius full throttle turn, that just isn't realistic. If it's lifting the RIGHT sponson, you either need to run the strut deeper or raise the back of the turn fin. If you're running a curved fin, raise the back of the fin for more bite. If you're running a straight bent fin, use it only for tracking and tighten the boat with the strut only. Try to keep the strut flat with the running surface (again check on table) at all times.
You boat might be lifting the sponson because you have left rudder input in to keep it straight. This is bad. Fine tune with the strut and fin. The rudder should always be neutral to track straight.
Once you get it all worked out and handling as it should, you can then try it with the wing back on and adjust it until handling returns to where it should be. Those wings can have very ill effects on a sport hydro though, so I would definitely set it up WITHOUT the wing first and take it from there.
Keep us posted. Don't give up. There really isn't much to it, and only through testing will you get it right. Those hydros run real well when you get the setup right. Don't forget, the prop has a LOT to do with the equation also...so a prop with more lift will have similar results to running the strut deeper for example.
Some pictures might help also, so feel free to post a few showing side and rear profiles of the transom hardware and turn fin.