I have one that I used to use for a yamaha 20 but as I no longer have the engine its up for sale. its in inverness but i could take it apart to post. Open to reasonable offers.
I need a trolley that will take a long shaft Merc 20hp (about 56kg).
P.M. a drawing of what you want can fabricate you one,wont find anybody cheaper,loads of 2x2,3x2,4x2 steel offcuts lying round my workshop,minutes to weld together for you.