Interior progress and a question

Howdy All! Had snow and cold last week so had a change of plans and started detailing on the interior. Cleaned all the interior fabrics, carpets, etc. Removed the instrument panel overlay, and polished, and waxed both it and the dash. Disassembled the speedometer and gauges, cleaned all the faces, and glass on the speedometer and clock, cleaned and polished all the infrared filters on the gauges, and polished/buffed the stainless and chrome. Rewound the windings on the clocks winding motor, as it was weak and would only do a partial winding. Cleaned and lubed it and the speedometer. It was a busy week! The question that I have is... the original owner of the car must have been a very heavy smoker. The interior was covered in a mixture of 60 years of nicotine and dried condensation. This mix was so heavy it actually ran down over the door panel fabric, seat back fabric, etc.. Warm water rinsing and blotting with paper towels, followed by repeated cleanings of upholstery shampoo took care of most of it on the fabrics. And Mequires polish took care of it on the painted surfaces, and woodgraining on the dash. Any suggestions for something that will remove it from the plastic of the steering wheel, shifter knob, and vent knob without harming it? Thanks in advance.