One of the biggest things will be removing the dry soil from the rug. Something that is 80 years old has collected a lot of soil. Of course it may have been cleaned in that time. However lay it face down on some grids (kitchen fatigue mats work) and run your upright vacuum over it for as long as you have time. Then turn it over and vacuum the front well. Cleaning should be done with safe for wool products and on the cool side, dont be too aggresive in the clean and you obviously need to do this off site. Check the colours are safe before using any chemical. Ideally full imersion would be the best way to clean but you have to have facilities to remove excess water. One thing you want want to consider is dry it face down on a dust sheet with a blower across the back. Paul you've done a lot of cleaning so will have good knowledge of practical to help you. As Jonathan says the silk can go hard or crispy but drying before, as and when its dry will help to soften this.