Hi.
My engine is 3919850: 400 hp.
is it right??

The 850 # is the intake number (400 hp oval port tri power . The engine casting # is located on the top left (drivers side) rear of the block . This is a larg # and should be easy to read . That # should be either 3916321 or 3935439 . Also , there is a casting date code on this block , located on the right side (passenger) , below the # 4 spark plug , just in front of the starter . This code should have one letter followed by 2 or 3 numbers . Let us know , George

You might want to get the NCRS Tech Manual for 69-69. It's got a TON of information on the original parts / numbers /options. The odometers are really easy to turn back, and many of the older cars go past 100,000 and then read 0 again. How do you know that mileage is accurate? You say it's already been disassembled? Do you have photos of the installation before it was taken apart? There are a lot of little things they did at the factory in 1970 (and I'm sure there are even more things in 1968) which generally aren't put back the same way by mechanics - like the washer on the rear shocks not being under the nut, but rather on the other side. If you could look at things like that you could tell if those shocks were likely not just original ones, but ones installed by the factory. This is just one little example. Many of these details are in the NCRS guide. Good luck with the project. :) ~Juliet