Scott, think your 6hp is about right -- right at the limit for weight aft of the rudder.
Yamaha 110lbs for an 8-4 became ridiculous for me to stomach, Just looked up
Honda OBs and found a 15 at 104lbs. Maybe you can HP-up to an 8 and keep
the weight the same with a modern motor $3400.
I can't deal with petro smells anymore. Kerosene, diesel, gasoline, strong solvents
like toluene acetone are out. Still grudgingly use naptha for decal/tape removal
but non-toxics are appearing. And I use a tiny amount to thin 2-part liquid epoxy
as a first coat sealer. Fossil fuel days are numbered. Expensive high labor lithium
must be on their way out. They're almost fossils by now, we need an efficient, less
labor intensive battery that will last for 20 years. Somebody is working on it!