my neighbor is selling a pair of moog #5390 w/ac but my car doesnt have ac and i know the 5390s are stiffer. will they change the ride height ?

Shows W/ or WO/ac here:
http://101part.com/coilsprings/chevy/8chevelle.htm
Look around on that page (search for 5390) and you'll find a variety of applications:
70 307 SW wo/ac and plenty of others listed.
You can find the spring rates here:
http://www.101part.com/coilsprings/Moog_Coil_Springs.htm