Willem,
PM me. I may be able to help you out.
Jonathan

Thanks for your suggestions. I looked at goBilda, but they seem to be sold out. I will try a servo expander, that should work with my old analogue transmitter.
Thank you all for this fast and helpful answers.

Why not try a large gear on servo connected to a smaller gear beneath the crane to give up to 360° rotation🤔

I forgot to mention, that the goBilda servos will also provide 360 degree continuous rotation with full proportional speed control. They really are quite nice units. One need to purchase the servo programmer, but they only cost $10 and you only need to buy one once.

YES. There is a very good set of servos made by goBilda, see their page here: https://www.gobilda.com/2000-series-dual-mode-servo-25-2-torque/
Both the Speed and the Torque versions provide 180 degree rotation out of box and up to 300 degrees rotation with a servo expander used. I have used the speed version, which is lacking in torque, to move turrets and torpedo tubes on my 1/48 Fletcher destroyer. I was very happy that, with a simple expander, they achieved 300 degree rotation, but I was disappointed by the low torque. I replaced them with the Torque version and could not be happier. Since that time, about 1 1/2 years ago, goBilda has come out with a higher torque servo. I can not determine if this new servo will give 180 degrees right out of the box, as the Speed and Torque versions DO.
The company is very easy to order from and is very fast and responsive. I Think that they would be the ticket for you.

Hi ,there are several high power servos but in a standard servo size. Usually metal geared and you will not need anymore than a 6 Kgrm /cm power.

However you will see several servos marked as 180 degree turning but they only work if they have a 180 degree driver.
So you will also need a servo expander unit to fit between the rx and the servo. These are incredibly small items about the size of 2 servo plugs. There is a UK firm makes them and there are several available from China. Expect to pay plus or minus £10.

But even if the servos are advertised at 180 or perhaps 160 degree movement they still require another unit.
If you are happy with electronics and can take a servo apart then add a 1K ohm resistor to each side of the feedback pot and this will increase the total throw of the servo. You will need a bit of trial and error here.

I do not know if modern computer tx's can expand the servo signal to match 180 degrees. I expect someone else will know.
regards
Roy