[Signman]

Marco

Know a little bit of the history of that car. Is your engine flat top or dish piston with 083 head? The HP you provide would be for the dish piston I believe.

Your high RPM miss can be the valve springs but the only real way to know is to take off a couple and check open and seat pressure. The hot ticket right now is conical springs, they have some good qualities but unless this is a max effort conventional springs at lower cost still go down the track.

Check evertything in your ignition. Don't assume because it new it's good.
One time I was having problem with the car slowing, after fixing it was slowing up again! The distributor was not tightened completely when syncing with ECU trying to find the first problem.
Look for dumb stuff.

Look over your fuel and timing maps to be sure nothing was changed by mistake; look over your set up in the software to be sure everything is as it should.
Ask me why I know this.........

Make sure you have fuel pressure and volume, it will miss upstairs if it's real lean. If you data log Air Fuel Ratio it will indicate, if you don't you should. Check the plugs too.