Hi
I split the problem somewhat differently, by using an electric hoist to raise the machinery, and temporarily fitting castors to the (wooden) bench.
The hoist is attached to a piece of timber, which is temporarily laid between at least 2 rafters in my garage, which is of a trussed roof construction. If I can manoeuvre around on these light timbers without worry, then I know it will easily take the weight of my ~100kg machines with ease, and should be no problem with at least 200kg.
The castors I use were from Toolstation, 100mm diameter and rated 125kg. Because the stock was limited at the branch when I visited, I got 4 swivelling castors (2 with brakes) for the corners of the bench, and 2 fixed castors for the middle of the front and back. All fixed with short coach screws (hex head).
I get the machine delivered to somewhere in the middle of the garage.
So I could hoist the machinery, position the bench underneath, and then lower and fix the machinery onto the bench. Then wheel the bench into near final position in the workshop attached to the garage, jack the bench up slightly and secure with timber blocks under, remove the castors, then carefully remove blocks and lower the bench.
The benches have a number of patches of heavy duty stair carpet glued under for cushioning; the workshop floor has a laminate surface, so the benches can be pushed into position without difficulty, even with all-up weights around 250kg.
I used this for fitting my WM16 mill and WM250 lathe, The castors are now attached to a small spare ‘bench worktop’, 900 x 600mm laminated from 2 pieces of 19mm ply, for general heavy-duty trolley use, e.g. moving my wood lathe and bandsaw to the ‘wood shed’.
Martin