Disks are nice and will bite well, but are not quite an mount-and-go prospect. The thing about disks is that you need a disk brake hub to attach the disk to, as well as a place to attach the brake caliper. The stock front fork leg will not have the lugs for a disk brake caliper, so you will want a new fork or have someone weld on mounting lugs. If you do not already have the wheels you are going to use, be sure to look for a wheel that can take a disk. And 12 gauge spokes are nice too.
The easy route since you already have a front mounting hole (for a front fender) is to get wheels that work well with side pull caliper brakes, and install those. You probably have a fender mounting hole on the back that would work as well. From what I have seen, there are decent quality side pulls for pretty cheap on Amazon, and you can install them yourself no problem.
If you wanted to go with a springer front fork, they have springer fronts that have the lugs for a v-brake already installed, which will give you more bite than a side pull caliper. And I think Venice makes a disk brake adapter for springer forks?
Personally, I am going with a Sturmey-Archer 90mm drum on my front, the XL-FD. They have them for about $70 on Amazon, and my bike shop said they could lace them into my current 12 gauge spoked wheel for pretty cheap. Those stop well, look old school, and are not bothered by the rain. If you are not running a hub adapter on the rear for your sprocket, you can get a 90mm drum for the back too.