If you install a 273 crank, with 340 rods, and hypers, you are gonna incur the cost of a rebalance.
Late teener rods have the same casting numbers as 340s, and early 360s; the difference being bushed or pressed pins.Otherwise they appear identical.
On the street, I wouldn't lose any sleep over using a cast crank. My 360 crank has been to 7000rpm probably thousands of times over it's life. It was balanced with bushed teener rods and KB107s, and runs a flywheel. The assembly has over 100,000 miles on it
