Some things to consider:
If you don't tap a beer every so often, the beer that is left in regular beer faucets can dry out and lock the tap shut. I suggest a perlick faucet as it seals without drying out. I've used mine for years without any "sticky tap" problems.
If you are going to have a tower on top of the fridge, the beer line in the tower will warm up to the ambient room temperature. This means that the first part of the first pour of the night will be very foamy as the pressure is different in the warm tower. Some way of insulating the tower or circulating the air inside the tower will ensure the quality of the beer in the line.
When cutting the top of the fridge, be very careful to avoid damaging the cooling lines (if there are any in the top) as that will destroy the cooling ability on that wall of the refrigerator.
If you're keeping it in the garage, you may want to consider some way of sealing the tap when you're done for the night. A plug will prevent flies or ants from enjoying your beer while you're out. A lock will prevent any neighbors from doing the same.
Probably not as direct as a link to a conversion kit, but hopefully this will help you decide.