71 SBC with no P/S or A/C. I know I have a head start with no P/S but it went better than many experience and I had expected.
I started with the drivers side. Noodling on the ways I had heard about jacking the engine up via the oil pan etc. but after eyeballing it, I decided to go a different route.
With the car up on front ramps, I used a bottle jack to the the front of the engine by the front left corner that is not covered by the oil pan.

Lifting the engine a 1/2 of an inch or so allowed the through bolt to come out and all of the block bolts to be undone. Oddly my upper rear bolt was hand tight.
The rear and lower bolt are straight forward and accessible from under the pan and frame "engine cradle". The upper forward bolt can be reached
with hands above the cradle but while still on you back on the floor, yeah!
Jacking the engine up about another 1 inch allowed the mount to be slid down and out with a little fiddling of the plug wire heat/RF shield.
Install was as "easy" as aligning the mount and getting the top bolts in finger tight, then the bottom, then torqueing them down. Lower the
engine until through bolt holes align and you're good to go.

For the passenger side there is a mirror block jack point just inboard from the fuel pump flange. Getting at the motor mount bolts and through bolt is tighter on this side.
The lower block bolt and through bolt can be had from the bottom, the upper block bolts I got from to top. Pretty easy once you get the proper orientation and realize the sockets have to
be angled pretty far down to seat. The front just socket, the rear with a few inch extension. Extra fiddly aligning the upper bolts on reinstall because they're blind but very straight forward.
At the end of the day I might have replaced OK original? mounts but they had pretty lengthy stress fractures in the rubber so now good for sure.
I went with made in USA originals as they were inexpensive and seemingly solidly built.

 

Nice photos and good text.
Many will gain from this.
Myself, changed engine mounts 3 times now in my 77.
(I've owned her for awhile).
Never had a problem with a block of wood on the oil pan and a floor jack. But I appreciate your nervousness to do so.
Many times for various projects, like changing plug wires. I have lifted the engine by the oil pan. Block of wood on a floor jack. Never an issue.
Even things like pulling the transmisson to replace a clutch.
Support engine with floor jack on rear of oil pan. Lower rear of engine to remove trans. Jack back up to put mainshaft back into place.
My oil pan is fine after 45 years of such repairs.

 

If something breaks and needs repair, like a motor mount for example. It broke because it's design was inferior from the factory design obsolesces. Only make stuff to last past the warranty period. So as a thinking mechanic I would search out better products that don't break. It's not a good sign when you do things the same over and over and expect different results.
On a low performance car Energy Suspension poly mounts are okay. solid steel mounts are actually the best.

 

That's a pretty narrow viewpoint. If someone backs into your car necessitating a repair is that because of inferior design? If an original motor mount failed, and I'm not sure mine did, 50 years after manufacture and used in a hi perf, very harsh operating environment does that mean it design obsolescence built in? I think not.
As a sometimes thinking mechanic, when I'm replacing a part that has lasted 50 years, I try and replace it with something that evidence might suggest would serve as well and last just as long.

 

I don’t remember which post it was on here, but somebody showed a picture of those original type mounts reinforced with two thru-bolts. The two spots with the rubber showing he drilled thru and put in a couple of bolts with tapered flat-mount heads. Retains the vibration dampening but protects from shear force when the engine torque-twists.

 

they have a metal hook on them by the bottom bolt holes so they would stop the engine from popping through the hood. in fact those new ones are essentially solid mounts that sit on a rubber pad. i am not nuts about using the pan. lift point is too far back. i use a block of wood under the balancer and unbolt both mounts at the same time.

 

Us older guys remember the notorious Chevy V8 motor mounts of decades past.
How many million were recalled? I do not know or care.
But back then, a broken mount would jam the throttle open. Not something to ignore, says GM.
Their solution was to place a steel cable around the drivers side mount. It was a cheap fix and avoided a class action law suit.

To this day, in the back of my mind, thinking, could it happen again? Could 50 yr old rubber mounts snap?
Hello Moroso Solid Steel. Goodbye stock units.