I just had a timing cover leak which meant I had to remove the balancer. I had to jack the front of the engine for that, and I raised it up arount 3" without loosening anything but the front mount. I would think that you could get the engine high enough to replace the mount without all of the extra work or removing the rear mounts, etc.

-Tim
'51 Chevy 3104 w/'56 235, 848 Head, HEI Dizzy, Corvette Cam, Split Manifold and Dual Carter YF's