Welcome to the site.
"What is it worth" are threads more often restricted from forums like this since they only become for sale ads and then break down to bidding wars. This is one of the reasons the sites that do have For Sale sections have the requirement (as we do) that prices must be posted with the post to eliminate this also. We carry the idea a little further by discouraging even responses in the discussion threads such as "I've got one of those I'll sell you" sort of posts since those are often followed by another offer to sell one and it takes off from there along with the discussion about the finish, proper application or remedy to the problem the thread started out on. Basically and bottom line most if not all forums stay away from this sort of thing since they don't want to become the EBay of old car parts. The only way around, and not really around the rules, is that if you can post them somewhere we do have a section titles "Seen On The Web " which would allow members to see and view a link to your page or posting somewhere and look and possibly help in that way.
Lately with the passing of friend some of us have been discussing the challenge faced by people in your situation. What you have agreed to is honorable but very time consuming. Don't think any one solution will be the answer. Some of the more common parts you should be able to research and find for sales ads on places like the SAAC web site. Things like intakes, pans and so on. Remember prices continue to increase of many of these pieces but most of the time conditions vary
I've see some hire for a price (flat fee or percentage), people in the business to handle these things. Some if this is a high demand or quality collection, hand things over to an auction house. Others take a year to sell the collections through local and national outlets but its tough and of course there can be all sorts or memories and in turn possible drama. Good luck with your efforts and thanks for taking on the task.
Sure there will be other peoples thoughts and comments. Let's just hope it does not become a thread for sharing a bunch of stories about what went wrong or ones not connected to your current need. Will give this a day or so in the current location then move it to the Lounge since it does not directly relate to the sites focus but it will still be seen and viewed there also.
Again Welcome