Sidaj,
Welcome.
Wooooow! A '68 Falcon with a possible big block Six. Check again to see if the head has a detachable intake manifold. Both the big (240/300) and small (144/170/200/250) blocks have a detachable exhaust manifold..
If you have a 170/200, the casting numberis on the back half of the intake log - between the carb and the firewall. The head will read C8DE 6090 - Letter. "C" stands for the 60's decade (D = 70's) "8* sands for the eighth year of the decade. "DE" equals a Falcon. 6090 is the casting # for ALL heads, and the letter (A,B,C, etc.) is for the engineering change. No-one has yet figured out all of the letters.
For a 170/200 block the nubers are cast into the block right in front of the starter. Use a flashlight and contort a little to look for these behind the exhaust pipe. For a '68 it should read C8DE 6015 -A. the 6015 is a block casting number for both 170 and 200. A 170 should have three "frost" plugs in the side of the block. A 200 will have 5 "frost" plugs.
If you really have a detachable intake, ask for casting info on the Big Block section. A 300 in your Falcon would be a real rarity.
PS When you are puttering around, go to your profile and add your location and your vehicle to your "interests". it save lots of time for others answering questions.
Good Luck
