Well first: I think you got a bit lost there on the nomenclature
A live axle means both wheels turn at the same speed even if both wheels are off the ground.
whereas a dead axle kart (one wheel peel) only drives ONE wheel (usually the left one)
and a differential kart has while being "live" a differential axle but it's sometimes too refered to as live (since both rear wheels are powered)
Engine shaft size and horsepower is in fact important..
with a 9hp engine you are on the edge..
technically (going strictly by the book) you need a series 40 Torque Converter
you COULD get away with a series 30 however (just order the correct driver bore of 1" of course)
it's technically rated for only 8hp but withstands a bit more without much of an issue.
The step down on your axle isn't important at all for this, since that's oly what the wheel hubs attach to, nothing the TC is actually aware of.
tyres are the nasty black rubber thingamabobs resting on the silvery rim which itself contains or is bolted to the wheel hub.
short: there is no such thing as a tyre hub
1" axles with stepdown can be found from Azusa (azusaeng.com)
pick the desired length and find that axle online (say at mfgsupply.com or alike)
You'll also need two more hubs
One for the axle sprocket (what you call live axle gear I assume)
that needs to be picked for the sprocket and axle diameter
(I personally like split sprockets since they're easier to swap... but whatever you like will do
as long as it's the correct chain size and toothcount)
And another one for the brake (I hope disc.. but even drums usually conenct bolt to hubs)
Nothing must ever be welded onto the axle!
very few exceptions, none in the karting world! (some atvs have..nevermind)
So all kart hubs are keyed and come with locking mechanisms of various kinds
(set screws, slitted with clamping bolts, self locking tapers.. etc)
Some require locking collars to prevent them from lateral movement (that's what PO welded for I guess)
most don't.
Once you picked a type and style, make sure to let us know before ordering, in case we want to give specific advice (on if locking collars or not or not working for some reason etc)
And when in doubt: always post pics!
'sid
