You can replace the main caps fairly easily, but you may have a scattering of smaller power supply caps on the amp boards. Usually 50 to 75uF or so. Those can like caps should be replaced at the same time.
Honestly, wet (electrolytic) caps in the 1980's were pretty crappy compared to the modern varieties. Much more inductance and ESR than the average cap today, so you can improve upon the power delivery and lower the noise a little by doing them too.
Honestly, wet (electrolytic) caps in the 1980's were pretty crappy compared to the modern varieties. Much more inductance and ESR than the average cap today, so you can improve upon the power delivery and lower the noise a little by doing them too.