Having been part of the chopper scene back when loooonnnnggg springers were the rage I can tell you that you need to know your math on rake and trail and how springers really work. Go here first:
Then buy a springer from Sugar Bear, the best there is, and he will nail it so that your chop will handle. Don't buy some cheap ass DNA springer or a knock off of some kind.
Also you should know that one of our tricks was to use the smallest diameter front wheel possible, 16's in most cases. That helps you a lot when you have a heavily raked chop. Do the math on a 21" versus a 16" and you will see what I mean.