How to get rid of understeer in a 1970 340

Reason I ask is I wonder if the body couldn't be flexing under torque when cornering. Are they easy to R&R? That I don't know. I have heard of people who bolted them in, and others who burned/welded them in. Some even went so far as to contour them to fit the under belly, then had a good clean weld the whole length.