IMO, the Countdown release is the closest to the the '68 you can get outside the '69 annual which is a little spendy these days.

It lost a few parts from the '68, like the disc brakes on the front, and some other bits, but if you are making whole cloth of a builder it's as close as you can get without breaking the bank.

Then the tool got sorta hacked up to do the Street Machine version that followed (in that execrable milk jug plastic) and came back around in the 90's thanks to Tom Carter's close consultation with AMT/ERTL.