How do you indentify a 400SB

[beaterC10]

I posted the same question on the drivetrain board. Hoping someone has the answer.

Is there a quick a dirty way to identify a SB400 that is still in the truck without the gymnastics involved trying to read the casting numbers on the back of the block.

I was hoping the balancer might be the tipoff like it is on a 305. I thought some of the early 400's had 3 freeze plugs per side instead of the normal 2.

The engine is supposed to be a '75 vintage that runs but has a miss. The guy thinks it is bad valves, but I guess it could also be a sloppy timing chain, worn out cam, vacuum leak etc.

Any idea what a complete 400 is worth. Probably more than a 305 and less than a 454.