Thanks for all the input guys.
As per Frank's suggestion I'll be checking the fuel pressure today and reporting back my findings. The fuel return valve is the brass variant and is not controlled by vacuum, rather a small pin on the bottom section that is pressed by the throttle linkage when at idle.

The exhaust smell is not sweet or coolant like at all and smells of fuel, another possibility could be some old oil build up in the muffler from before the rebuild.
With the float set to 23mm I'd assume that this is the "lowest" setting in the fuel bowl as a thinner washer would in turn allow more fuel to sit into the bowl by holding the needle valve higher. Needle valves for float level are brand new and were replaced, I'd like to hope they aren't sticking but I have to entertain all possibilities

Compression has not been measured since rebuild but have only approx 10 miles on it since re-assembly.