The fork must say tapered from 1 1/8 to 1 1/2. Rake is the distance the bottom of the fork projects forward from the line through the center of the head tube most commonly these days about 43 mm on a road fork. Rake is very important with regard to bike handling and combines with head tube angle to produce the handling determining characteristic known as trail. You need to find out what rake was specified originally for your frame and match that, or else you risk really screwing up the handling of the finished bike.

There are other fork characteristics that also need to be addressed like the distance from the fork crown race to the front axle. That should match the original specification as well. Small differences are not catastrophic, but it is not like you can just ignore it either.