Cruise friendly low 12's with a 340 Dart

Your drive shaft can be cut down easy enuff. The OD tranny is better IMO than a gear vendors OD unit that costs 3x's the price of a fuly rebuilt/worked up trans and converter.

costs for.... This is homework best done yourself. Start at Jegs and then summit, Manciniracing.com, just keep fishing around

intake ........seriously speaking, I'd do a RPM or equal.
new carb ...What ever carb you go with, it just has to be one your OK to work on yourself.
headers.....the tti's are all your going to need.
heads.......The OE heads are capable of propelling you into the 12's easy.
cam......... Besides the one I mention earlier, the duration should be speced for the RPM range your driving in and keep in mind the OD ratio when doing so. Remember, those 3.91's in OD are going to drop a good bit to 2.69. That gear ratio isn't going to like a cam duration (@.050) of 244 while chuging along the hwy under 3,000 rpm's.

Do some searching on line for pricing. Great way to kill some time.