Engine numbers

Hi all just received my 67 Dart gt from Johnburg ILL,4 months after the deal was done ,long wait but it was worth it at the end. Was alittle dissapointed as some one had helped them selfs to my fender Tag while she was in in LA in the holding bay, not to mind as i have photos from when the car was inspected and have all the documention to go with it so i will have to contact Galen Glovier to get that replaced.I was trying to find the engine numbers to see if it was a numbers matching because everything from the fender tag was decoded and was correct so i wanted to see if the motor was also correct as well,to my supprise i could only find 2 digits which were very faint not legitable,4digits which you could read easy than under it was a 8-25 ?. Than i started to dig a little further and got the casting numbers off the block and found out its a 318, (2806030) was built 3.4.66 and was made at 12.00pm dayshift, but what confusers me is this engine number,its under the drivers side cylinder head .The machine marks on the surface dont look like its been tampered with, only some slight sand marks which i did to remove the paint for verification.The engine has the 273 4 barrell carb, manifold, twin point dizzy, aircleaner, all the gear like the 273 Hipo commando engine but is a 318 in diguise. Would or could some one shed some light as to whats going on.Ive head Chrysler did some weid things with their warranty work when engines were replaced.Thanks P.S will post some photos soon as im doing some front end work at the moment,new rubbers , ball joints etc etc