Need help with stainless liner tee installation

[stihl025]

Okay, need you help and expertise. Just purchased a 25' 6" stainless liner kit that comes with the flex liner, 2 part tee, rain cap, and top plate. The chimney that I am installing this in is a 21 foot tall, 8" round terra-cotta lined chimney. It has an iron 8" thimble already mounted in the masonry. 2 foot below that is a 9"x7" cleanout. What should I do with the thimble in regards to making the connection from the tee to the stove pipe?
1. Do I need to chisel out the old thimble and install a new one (6" thimble)?
2. Should I just run the black stove pipe into the tee and mortar around the gap?
3. Should I just mount a new 6" thimble inside the existing 8" thimble?
4. Just use a 6" thimble trim ring and screw it into the old iron thimble, leaving an "air gap" between the two thimbles?

I really can't find too much info on this portion of the install. I am really not sure what to do here. The chimney and thimble are inside a complete concrete basement with no combustables around. Help...

 

[Festus Haggen]

I'd say #2, but hard to tell for sure without seeing a pic or drawing. I pulled my liner all the way down and out of the thimble, then used a 6x6 adapter to hook my black pipe to the liner. Was an option when I got my liner to either get the tee or end adapter (not sure what they call it, just a "snoot" that adapts the gear-clamp liner fitting to the black pipe). Can you get to the bottom of the tee once it's in there from the cleanout? The main purpose of the tee is to drop stuff that you brush down out the bottom, more intended for an insert-type install. Had to really reef on my liner to get it around the 90, so be careful with that.

 

[stihl025]

Pics

I'd say #2, but hard to tell for sure without seeing a pic or drawing.

Ok, here are some pics to help you visualize. 8" thimble and cleanout that is 24" below the thimble. Not sure if I will have to create an extention for the cleanout of not.