You need a 1" threaded fork if you want to minimize the work needed.

You should have a bike shop remove the crown race from your old fork and put it on the new one. The hiccup that can occur at this point is if your fork takes a different sized crown race. There are two sizes that are less than a millimeter different in diameter. I believe the different sized came about as a result of different material being used.

Then install the new fork...and do it right.