Matt, It depends on what you are building.... A custom one rider cruiser might do better with a shorter and softer shock, while a Cafe' bike or racer tends to "want" a stiffer, longer shock...... But it also depends on YOUR stature, and the bike.... I'm 5'7" and 165# and don't need longer or real stiff shocks.....especially on a smaller lightweight bike..... A 450 is no lightweight, and if you are 6" and 200# you may require heavy, long shocks...
There are other considerations as well....Lifting the back, or lowering the front (or both)essentially reduces the rake albeit only slightly....this can help make the bike more "nimble" and quicker responding to turning, but may hurt high-speed straight line stability....Lowering the back or raising the front makes it inherently more stable at speed, but sluggish to turn.... EVERYTHING is a compromise and must be "adjusted" for the needs of the rider/bike combination and its intended usage..... For the same reasons that I can't specify ideal gearing for your bike, I can't specify YOUR optimal suspension requirements, I can only indicate general guidelines......
I hope this helps you decide what COULD be best for your needs..... This is a greatly simplified explaination, MANY more factors are actually involved....( Trail, COG, weight percentile distribution, etc....) .....Steve