Crate Motor

i would sell the 340 in a heartbeat, all it is is a bored out 318
you will be much happier with the 408 in it (did i mention blueprint has warranties on their engines)

on top of that, people obsess over the 340 to the point that you probably end up spending 1-2 thousand to do the swap (especially if you sell the 340 in the winter when your not driving it anyway, and the buyer can hear it running in the car)

besides, "numbers matching" and resale value is great if your a flipper, but it means squat to a car guy who actually drives and enjoys his car