There is a plastic spacer that goes between the carburetor and the block maybe that is missing if not check on Parts Tree Repair Clinic the may have a video that will help good luck.
Was it a genuine Honda ignition unit? as i have had bad after market units, check the air gap between the flywheel and the unit this should be around 0.3 mm, finally remove the cutout wire completely from the coil and try for a spark again.
There are two hoses, the fuel hose which has the filter on the end in the fuel tank, and a return to tank hose, the fuel hose goes to the lower of the two connections on the carb, the return to tank hose ( which is normally clear ) goes to the higher connection on the carb
there is no code in the serial #. I have a 5018 4wd.
Called them and they were able to locate the Dealer it was sold to and the date sent to them, and the day I bought it as the dealer registered it sold.
American Honda Power Equipment Division
4900 Marconi Dr.
Alpharetta, GA 30005-8847
Customer Relations
Tel: 770-497-6400