The prop strike engine will be a lottery. You might be lucky and the crank is fine, you might be unlucky and have £6k bill before you do anything else.
If you buy it after an inspection - and it passed then the price will not be discounted anything like so much - but it will still have had a prop strike.....
If you are buying second hand get a thorough inspection, check the history and that probably means visiting the last place it was based or used. Engine cores have a significant value and if they are really cheap then there is usually a very good reason. A lycoming rebuild with cylinders, camshaft and all the SB260 bits is going to be circa $16k and likely that in pounds, adding a new crankshaft fairly inflates that bill.