I think the project is a solution looking for a problem. But that is just my opinion. I sincerely wish you the best and I hope you and your new 'Frankenbike' have many thousands of safe and happy miles together.

Some advice:
First, on caliper brakes, the higher up the pads are mounted in the caliper the more braking power you will have - moving the pads closer to the brake pivot changes the leverage ratio in the caliper.

Having a bike set up so it can only use filed-down brake pads is asking for trouble. In my opinion this is acceptable as a temporary measure only as it can result in the brake pad rubbing and damaging the tire if you are not careful, and it complicates maintenance.



If the brakes do not quite reach, consider making or buying drop bolts as described by Sheldon Brown.

Using a drop bolt to lower the mounting bolt allows you to have the pads higher up on the caliper so they make the correct contact with the rim, and so they are closer to the pivot and give you more power.

Generally speaking, there are three ways to correct this:
1. Have the frame modified
2. Use a drop bolt
3. Find another model or style of brake that has a longer reach