A body with an A833 and a Gear Vendor installed

I know Passon has a kit to make your car basically a 3 speed and 4th with OD. Better gearing than the factory OD tranny.
Conversion Kits
I’m not sure if they sell a kit anymore? Hasn’t been listed for a few years. Seem they want to sell the entire trans already built? I inquired and the answer I was given… any thoughts on this? I’m not wanting to drop $3,600+ on an entire trans. But I would buy a gear set kit.