A-type keg; open it?

I need to supply beer in an A-type/leffe style keg for a bar. It came as a regular used keg, not cleaned. I crammed some hoses together so i can push into and out of the keg from a corny; i've got oxyclean in there, but i haven't opened the keg. I never use anything but ball locks, can someone who uses sanke or A-types tell me, do you disassemble these between uses? or is it fine to push oxyclean, rinse and then sanitizer through and call it good? i'd hate to have my ipa come out with the belgian funk of whatever was in there before, served to paying customers. I've seen online how to pull the spear on this thing but i need to have it at the bar in a few days and i don't think i'll be finding that tool anywhere soon!
This is the valve on an a-type btw.
Thanks!

I would remove the spear and use a brush, keg-washer, etc. Why take chances.

Have a look here on how to open it.

MC