I was trying to sell an engine here in ireland a couple of years ago and every breakers i went to said "sorry any cb-1's we get in the first thing we throw out is the engine, because nobody ever needs them"!
That really doesn't surprise me in the slightest, but I'm still glad to have the spare (even if just to play with), it still has it's starter, water pump, speedo cable etc so the attached spares are worth more than I paid for it!
The bike came with a spare set of carbs too with throttle and choke cables when I bought it so I'm slowly building up a garage full of parts I'll never need. I have got a spare pair of wheels which are in better condition than mine so might have them powder coated at some point in the future, they also came complete with discs and sprocket carrier etc, but the rear had a virtually new BT45 on it!