I guess I am wondering if there is any "rule" for non-numbers matching car pricing. I have seen several
cars that were originally 350 V8's and either have replacement 350's or moved up to 400 engines. Of course
other things come in to play as mentioned: overall restoration and other upgrades or replacements. I guess it just comes down to the big picture. Some stock 350's ask big dollar amounts ($38K) as mentioned earlier in this thread and folks seem to feel (without seeing the car) that a more accurate pricing is in the 20's. Then I've seen a car that has a model/year correct 400 engine and tons of upgrades and new this, new that and asking $25K. Which sounds like a bargain despite non-numbers matching. And when looking at other muscle cars (Mustangs, Camaro's, etc) they mostly have non-numbers engines/trans and seems to be expected or the norm.

So I start asking myself, self: should you not care so much about numbers matching?