First...I wouldn't convert to percussion...flintlocks were used longer than any ignition system in history...ove 200 years...a good flintlock is as reliable and almost as fast as a percussion....A .32 is great fun, and a good gun to learn with when it comes to muzzleloaders....If the lock is a Siler or Durs Egg...thats about as good as it gets....If you are having ignition problems, I might can help....I have been using flinters since 1977.
If you want to convert, you don't need or have to buy a percussion lock...Use what you have, it will be more historically correct....remove the frizzen, frizzen spring, grind or cut the pan flush with the lock plate, remove the cock (hammer) and replace with a percussion hammer.....Then remove the touch hole and install a drum and nipple....If you aren't comfortable doing this yourself try to find a smith that specializes in muzzleloaders....Good Luck