There is no point in atempting too much 'high end' modifications since the source and circuitry is only mediocre. Panasonic or whatever caps would be fine and metal oxide resistors. NE5532 or 34 are not particularly bad op amps and probably better than the originals although you should get the lower noise specced versions. There are many others to choose from so fit GOOD sockets and you can play. Ectra RF bypasses would probably help.
Unless you have the equipment to actually fully test your mods limit your enthusiasm to simple replacements. Different op amps may oscillate.