My tips are:
Make sure its the switch that is faulty by bridging the leads which go into your old switch. If wiring and bulb are okay the stop light should go on
Check the length of the banjo bolt and buy one which is closest in length. Slightly shorter may be better than slightly longer.
check thread pitch between old and new. This should be OKAy but laying the threads against one another should confirm
fit and tighten enough to stop fluid leakage. As you are working over th etank I recommend putting a plastic sheet over the tank to catch any fluid leakage.
Connect new switch leads to the old brake light leads. Conncectors should be standard but could need replacing
Bleed brakes. This can be a pain but you need to get any air out. If it still feels slightly spongy but no bubbles are seen at caliper end, tie brake lever hard back against handle bar and leave over nite. Works wonders in getting those last bubbles out.
