Three more common rust spots:
1) Windscreen sides trim clips - usually not the body
2) Right rear small window lower lip of sheet metal - more a 140 problem
3) Chrome bumper underside, especially rear

Even body panels are available new, if you are willing to import from Europe. I import a lot of stuff from www.scandcar.com to where I am in New Zealand, because Volvo started here only with the 240 series. The 140 and 164 is identical from windscreen back. The B20 and B30 engine parts are identical, except for the number of cylinders and the distributor. Electronic FI is just an electronic carburettor, and requires tuning (open loop control as opposed to modern closed loop control). Mechanical FI work great. There was also a 2-carburettor version, but that was on early models. The B30 is a great engine.