Numbers Matching?

Ok so I have a dilemma I am hoping to get some advice on. I have a 73 duster that was originally a 340 4speed. I bought it a few weeks ago and it has a 318 that has shot rings and smokes pretty good, the weather is really nice and I want to drive this thing so I want to get something in the car that doesn't smoke so much so I found a 30 over 68 340 bare block w/the caps. I sent it to the machine shop and it has pitting in 2 cylinders. He says it might come clean at 40 over other wise I have to decide on 60 over or sleeving it. so I starting looking around for other engine options and found a complete 73 340, just needs the top end put back on I guess. but he wants $3000.

SO, does having a date correct 340 increase the value in the car over the 68? the serial numbers won't match?? so does that really matter? I could save that $3000 for a stroker kit and cam, then later on do ported edelbrocks/w2's ? I just don't know enough about the numbers game to really make this decision alone. Any help is appreciated.