Going carb would be a waste and a step backwards. If you can tune a carb, you can tune with EFI.

The breaking up at high speed/RPM you speak of is because WOT is open loop, and I would guess your running lean. Alter your VE tables, and watch your wide band in these ranges. No factory chip (305/350/whatever) is going to *work* for you, some might have a few attributes to fit a certain situation better at times than others. I wouldnt look for pointers by reading other chips. If your engine isnt knocking or pinging (read knock counts too) then you dont have too much timing. A lot of timing is not neccessarily good, but most often extra timing will run better than too little.

Get a timing curve that doesnt knock or ping, and correct your fueling from there. Then you can fine tune the timing and fueling until you get something you really like.