Sure, lower the sensing arm on the LSVP to lessen rear brake bias.

Pad/shoe wear is not a good indication of brake bias.

The method I've usually heard for checking bias is to find a wet or gravel road, get up to speed and then hit the brakes hard. If the rears lock up first, you have too much bias to the rear. If you can't get the rears to lock up, the add more rear bias. Adjust so that fronts lock up just before the rears.

You just want to set it up so that the rear doesn't lock up first because then it will try to swing around on you, like when yanking the e-brake. <img src="/forums/images/graemlins/lol.gif" alt="" />

if the brake lining is cracked all the way through (or even more than just a heat crack) just replace them. the price of rear brake shoes is not worth the sudden failure if the shoes come apart (brake lockup or worse, no brakes at all)
replaced the worn out wheel cylinders then drive it. if it is not ok then adjust the proportioning valve as needed.