Not surprised. Big dollars that's for sure.
The stigma with 253 is mostly because they killed red 253 with the two barrel carny. Blue 253 go well with the quadrajet and electronic ignition.
People have been saying for years that good 308 blocks are getting hard to find. Most have been bored out 60 thou by now.
Personally I would put a fuel injected 5 litre in. I think I will go that way with my sandman.