I did this one time on my 1979 245 w/bazillion miles. I have only front wheel ramps, with the car up on them, I put a hydraulic jack, not an automotive floor jack, under the oil pan with a piece if 2x4 atop the jack top. This allowed me to control the amount of rise from under the car.

Next I removed as much as possible of the road crud/grease/stuff from the cross member mounting bolt area. There were several pounds, put a newspaper down to catch it. With a little lift on the jack I was able to loosen all the bolts on both sides. Then I lifted a lot and with one side still bolted down, the other side went up enough to remove the motor mount and both brackets.

To install I manuevered the brackets and mount into place with all bolts/nuts very loose and tightened things in stages. The job took a lot of maneuvering and finagling, there is surely an easier way, but it is a very DIY job. Fortunately I have a concrete driveway under my shade tree.

I saw a post recently about transmission mount. When that softens it allows the fronts to get bad. They said there is a taxicab/heavy service trans mount, dealer parts, that will keep the front ones good a longer time.

Good Luck, Bob