You can run up to a 76 crank without doing anything to the case, but the rods will need a little clearancing where the bolts are...or is that a 74???....
... i know a 74 will fit for sure....
I would stay away form a cast crank like the plauge, but that's my opinion.
Its just extra insurance knowing the heart of your well balanced engine wont snap if you wanted to have a little fun.
Maybe wait a while till you can get a Scat Volkstroker 2 kits, (that cast crank is the volkstroker 3 kit)
These are more expensive but, well, in the end you have a more reliable crank....you got what you paid for.
For the VS 2 kit and full flow parts and pushrods, etc, etc...go to aircooled.net
They have a full-flow kit, with modified and blue-printed pump and everything you need for I think $130. Also, if you get your carbs here, they help you set them up with the right jets and stuff. Check it out....
I wanst aware that CBP was selling their 76 cranks for the same price as a 69....i'll have to check that out...I havent bought my new crank yet soo....