Springer front ends look cool, but they ride like crap. There is no damping in them, and they don't have a lot of suspension travel. Now, 6" over tubes in your stock forks Will have damping that you can adjust with different weight fork oil, but the rake/trail of your bike will be way different, and it will handle poorly.
Just had one come through my buddy's shop, and it had 6" over tubes, and a Harley side stand installed, it leaned over so far, that it was a real bear to just tip upright to ride it. We took off the Harley stand, and grafted on a longer one from a Suzuki that stopped the radical lean to the side... but, the bike LOOKED cool lol.
If all you want is a cool looking bike, go for it. Or if you can find an Amen Savior frame with the springer/girder type forks, your engine will slip right in, giving you the old school chopper look.
Charlie