With mail order parts yes 50 cents on the dollar is going rate unless it looks like it just came out the package.

The problem is with engines you can't always do that. A lot of guys pay way too much to start with. But, 50 cents on the dollar for a builders advertised price is about right. Most of us can build cheaper than that and refuse to take a 50% cut on a good build.

If you part it out advertise parts on the high side but, negotiable. This way you are protecting yourself from giving away the best parts. If you can do well on the harder to get stuff and get most of your would be cash for the engine sale then you can afford to sell the rest at a negotiated price. Don't sweat it. I was very surprised how much of the stuff I thought would not be worth much was actually what added up the most together.

But, there is no crystal ball. Just got to take a chance. I would recommend doing what others have suggested. Try to sell complete first. You don't have to have a fire sale yet.