Edit: found some pics: Thread 'Zeda 80 starts but won't drive'
https://motoredbikes.com/threads/zeda-80-starts-but-wont-drive.64291/
Stock tuning on the carbs sent with the kits is super rich even close to sea level.
Most riders run 25:1 conventional for break in and 32:1 there after. It is your engine and you can do whatever you please but I believe the advice of 40:1 cradle to grave is wholly malicious. Its not exactly a conspiracy theory but some joker selling a stage infinity custom isn't exactly trustworthy.
Assume a 26 inch wheel, it is my opinion that your gearing is too tall for a pre break in china doll. Break in greatly helps with torque but since you're four stroking and pre break in it will be super anemic, explaining the relatively poor performance. Sounds like you're getting less than 1 horse power out of it at present. I have athlete's asthma I can make those speeds pedaling my regular bikes. These kits can run around 2.5 hp at 7k after break in with a good tune.
Edit: This bit is irrelevant for this build but I stand by it.
Getting ahead of myself but, what is your braking like? I hope its not a coaster brake only. The sensibility of a coaster brake is contentious for this application but I believe a well made coaster brake, when modified for improved performance and durability is sufficient provided a properly set up front brake is used.
Here's a great video on such modifications. And a brief list explaining my understanding of the reasons why.
High temp grease helps with overheating issues inherent to all drum brakes, which a coaster brake is.
The chromoly axle is stronger but less ductile, however since the bending of an axle makes it FUBAR this is no problem.
Chamfering of the pads helps with grease flow, which helps with lubrication and cooling.
Removing the bearing cage and installing more balls reduces the load each individual ball has to support, thus increasing the service life of all the balls.
Would love to see some pictures of your build!