Replacing a cooktop range with a range/oven

I'm looking at a used class A to buy but it has only a cooktop. My wife wants an oven (not just a convection) combo. A complete new stove is about $4-500 and it doesn't look like much of a job to cut out the drawers below and install a whole new unit. Has anyone done this and is it as easy as it appears it might be? Thanks