[SFfiredog]

A 410 is basically a 390 block with a 428 crank. All the other components are nothing special.
I pretty sure the were only available in Mercurys.
With brand new 428 cranks avaliabe from Scat, the price of a running 410 motor hase come down a bit. It really depends on the condition. One person's fair price could be too high or too low to someones else. For me personally, for a good rebuildable 410 core, I would pay $500.
--Mike