>>Could you imagine a Honda engine under the hood of a 1970 Dodge Challenger? Honda makes great engines no doubt but in this instance it wouldn't be a good match.<<
The current V-6 Honda/Acura engine is more powerful that 5 of the 1970 Challenger engine options. It would easily power the Challenger to acceptable performance levels at that time and with greater efficiency/less pollution/less noise.
Don't forget that today's engines are rated bhp (brake horsepower) i.e. the power available to the car at the drive axle. The horsepower ratings in the 60's and 70's were overstated in that regard. However, and to be fair here, many manufacturers underrated some motors due to potential insurance problems. Good examples of this are the Chevrolet L-88, Z-28, and ZL-1 options. Chrysler's 426 hemi is another example of understated power.