This is a job you could probably tackle yourself, especially if you can find an identical replacement mount.
Note the position of the mount itself (they are adjustable on the engine bed) and the height of the nuts clamping the flange from the engine. Prop/wedge the engine somehow, undo and remove the offending mount. Slip the new one in place, set the adjustments as you found them and snug things up.
If access is really difficult, or the arrangement is such that you cannot insert the new one without seriously affecting the original position of the engine then you may need to get an alignment check after the job is done. This too can be done yourself, and you will likely find good directions in any of the oft-recommended books found elsewhere on this site. (Dan Spurr's and others)
Of course the easiest way to do this is to pay someone else!