All 4 cylinder Mitsubishi carb'd engines use the same bolt pattern for their mounting studs. They share the same design with Mazda. This shouldn't take 20+ hours to set up, more like 1.5-2 hours to mount the carb and adapter plate and have the throttle cable hooked up. Add maybe 0.5-1 hour to install an electric fuel pump depending on how you choose to do it. Things to keep in mind - the Weber has an electric choke so you will need to block off/delete the coolant connections for the original carb (unless you're lucky and the stock Mikuni was also electric choked) I removed the heater/coolant barb on the manifold and used a straight threaded brass barb to connect up the heater hose and threaded a metric grub screw into the coolant port that is under the carb base in the manifold. You will also need to delete a bunch of vacuum connections - the only one that matters is the distributor vac advance.
You have 2 options for Weber carbs - the 32/36 (the go-to carb used in most installs) or the 38/38 (becoming more popular and is a slightly more modern design) The 4G52 is not a common engine now but I've always viewed it as an unsung hero. It's more rev happy than the 2.6 and with a couple of minor mods you can get good throttle response out of it and fatten up it's midrange torque.