If you built your ROPS, you obviously have decent fabrication skills. cadplans.com has plans available to build a 3 point backhoe that can be made to fit most tractors. They sell just the plans, precut parts that you weld together, or the most complete kit has the precut parts and all the hydraulic cylinders and fittings. I'm not sure what the hydraulic flow capacity of your Iseki is, but it is likely it will run a backhoe. It's just a matter of how fast things will move. An option is to use a PTO driven pump, which would create an independant hydraulic system. That would be more expensive, however. Try the build it yourself forum, I'm sure there are lots of threads about cadplans kits.