If you have a set of calipers you can measure what reach you'll need and then go from there. You could do it with a ruler too but you'd probably want to deflate or remove the tire so it isn't in the way. Just measure from the hole in the fork to the center of your braking surface. The only long reach calipers I've used have been Tektros which as you said aren't the greatest
There is a simple solution to all your problems...
