Welcome to the Forum! MTD eh? Well, MTD's aren't really any good for offroad use. They use a vari-drive belt system, an FNR transaxle, cheapo frames. But anything can be done. Hydrostatic transaxles are the same way and mine holds up great.
Now, my advice is that these MTD's (in top notch condition) are maybe worth $325, so, I'd run it anyway, even though it'll probably destroy it. So getting pulleys aren't too hard to find, but the type of drive system they use uses 2 oddball belts. I'm sure there is something you can do to get rid of them though. I haven't pulley swapped one yet so I know nothing about modifying MTD's, but I have one planned.