Picked up a '68 Dart two weeks ago at a local show, bashing it with the bits from the L.A. Dart.
First steps:
1. Cut the hood free from the L.A. Dart, fit to the Revell '68 body
2. Cut off the front fender "corner extentions" from same
3. Also remove quarter panel "corners" from the '70
4. Remove the same corners from the '68
These corner pieces are separate on the 1:1, so that'll make it easy and accurate! Looks like the hardest part of this conversion will be scratching (or modifying a kit piece that's close) a front bumper, and adding the correct shape/extension to the '68 trunklid.
Glued the front and rear valences in place on the '70 in preparation for the cuts