3.5 swap?

So details first. Looking at a 67 dart 4 door. It's a basic model. Slant 6 auto. Needs a motor. I work in a salvage yard and right now we have a wrecked 06 3.5 auto charger motors no good but I can pick up the car for 400 and a good 3.5(the one in the car had oil pan damage and burned up the bearings) for 600. I checked and the dashboards are almost identical widths do I'm thinking it would be cool to swap this motor into the car. Thoughts? Hemi would be cool but a simple basic v6 would be great for daily driver reliability.