Well, I'm going for it!
Picked up the '68 Dart two weeks ago at a local show, so here's what's going to happen:
1. Cut free the hood 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.