More than likely you can do a "Full Frame Replacement" with what you have without chipping away your stucco. Your 1977 windows should have a 2" brickmould around the window frame that attaches to the exterior wall. By removing the entire frame and brickmould from the opening you'll be able to attach the nailing fin of a new window in the same spot. It all comes down to the proper measuring for the new window. Depending on your existing windows and the kind of sill they have will determine the new window sizing. When I measure these type of windows for full replacement I measure the width from outside of the brickmould to the opposite outside of the brickmould. In the industry we call this the "Brick To Brick" measurements. I do the same thing for the height from the top of the brickmould to the bottom of the sill. Depending on the sill slope of the old window and what type of window it is determines how much I'll subtract to get my unit size. The width is easy because it's almost 99% the same on all window types. I subtract 2.5" from the brick to brick. This gives me my "UNIT" width (not the rough opening). In most cases I subtract the same number from my height with any double or singlehungs. This allows enough room for a 2x4 or 2x6 under the new window. Most of these windows have a lip of sheetrock or plaster that comes up under the old window that allows this new board without altering the inside opening. By placing this board under the new window we have something to nail the bottom nail fin to. If ordered correctly the new windows nail fins should lay right back in the existing opening without to many issues. We then bend our own custom capping to cover the nail fins by snapping it into the accessory grooves around the window. Ounce completed and caulked you'd never know it was a new window.

I would strongly recommend a professional on this kind of replacement. The money would be well spent. Good Luck!!!