30 years ago I bought a used Mercruiser Boat Engine (350 Chevy) from a dealer. I wanted to here it run so they just hooked up a battery and gas plus a water hose and started it up sitting on the concrete floor! I have since done it many times except I just blocked them off the floor with 4 X4's. The concrete scratches the oil pan.
You could just build a wood frame strong enough to hold the engine very easily. They won't move around, just a little vibration.
If one has a tractor splitter stand I would think you would have one right there,
the stand I built (do not have a picture of it and a neighbor has it), is a cross between these two pictures, it uses a small Hydraulic jack on each side to raise and lower for fine adjustment and has 4 wheels for stability and it has a diagonal brace for moving the front away from the rear, but only has the single up right working much like the trailer jacks, in the one picture.
This is what I came up with. It's hooked up to a B7800 in this picture. It well also fit up to my L4240 for sure, but should work on about any mid HP and down.