I have a 1997 f150 2wd, for some reason I cannot understand the lifting of the front and rear of the truck. I am redoing my front end steering and all around suspension, I bought the 3 inch rc lift I am wonder if I can throw on a 2.5 inch coil spacer and how big a block would I need in the rear to keep the truck leveled.

 

Generally the nose is 2" lower than the rear. So if you go up 3" in front it'd be 1" in the rear.
But w/o measuring your trucks unaltered heights this is just a guess.

Basically you have to subtract the distance you need to raise the front to achieve "level", as I described above, from the rear

 

I believe 2 or 2.5 inches is the limit that you can lift the front of a 97-03 4x2 with coilsprings or spacers. If you go taller, you will need new, longer upper control arms in order to get the alignment within specs. I would suggest installing some adjustable camber bolts while you are doing the installation. Some lifted 4x2's need them, some don't but it would be cheap insurance in case your truck does.