Have you stripped down the front brake as I suspect the metal castings for the calliper will be ok and just need new seals and pistons. The disc might be an issue if it has warped or badly scored but second hand discs are risky…unless you can find a write off locally that has had recent new discs.
The mounting bracket will need a clean up and you will need new hoses. I don’t know where you are but Bigg Red in Worcester https://biggred.co.uk/ can supply all the bits or you can send your front calliper for them to rebuild - there is an art to fitting the dust seal as that provides the springiness to retract the piston and stop the pads rubbing on the disc, (there are videos on U-Tube that will give you an idea of how tricky it is )so unless you have done it before you are better off letting someone else recondition it. The only way I could imagine the brake catching on fire is if the piston sticks in the “brakes on” position, and that is usually due to a rusty piston and/or a worn out dust seal, in which case the other side is probably in need of reconditioning as well.
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