I'm sure it's possible. But you probably need to check with a dealer or parts source to see if the master cylinders are the same internally and if the valve (not sure of the name) that distributes pressure to all 4 wheels is the same. Drum brakes may have different fluid requirements; I'm not positive if this applies on the MX-6 but it does on another car where someone toyed with the idea.
The parking brakes will be different, and you'll need the calipers/rotors and maybe different hubs (all of which can be had from a junkyard surely). If the fluid lines are different you'd need those too. Your best bet would be to park a drum brake car next to a disk one and see what all is similar / different.
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