DogBoy

I have a JTS with canti's, but recently I've started riding more hills and the performance is kind of scary on downhills. I'm a big boy (230) and it can take quite a long way to slow & stop. I've thought about buying a project 2 disc fork from Kona and putting a disc in front, but I don't really know what's involved in changing a fork. I think I would need a new fork, new hub (with disc slots), new brake & cable/housing (and have to re-do the bar-tape). What am I missing? Is this the kind of thing I can do myself? (except for cutting the steering tube) I've replaced derailleurs/cranks, adjusted canti brakes, changed stems/handlebars, done bar-tape etc. I'm afraid of anything involving the headset, so if I have to adjust/remove the headset I'll have the bike shop change the fork for me. I think the cost of this may be greater than the benefit so I'm leaning toward not doing it at the moment. I just want to be able to get all the costs figured out before I make a judgment. Thanks.