Limits on opening a piece?!

There is a limit.

If you want a gigantic tip opening piece, buy it that way,

don't ruin a perfectly great classical mouthpiece.
If you keep trying to open up a piece, the tip thickness will become so thin, and the side rails will become so wide, forget about it!
There are too many butchers out there who wreck great vintage mouthpieces!
It makes me sick.
Get on the phone to Mouthpiece professionals, and let them make you what you need. Don't ruin another piece.You can always cut away material, but you can't put it back.

Listen to MoJo and Sigmund....
If you want a piece that big...
.140" for a tenor is a bit absurd, that's bigger than my Baritone saxophone mouthpiece, (Otto Link Hard Rubber 8, .120")
Buy it that way, if you can, I don't know if Babbitt's Otto Link even go's up that far...you would need to play on reeds that were strength 1,1 1/2, 2...for a piece that big ...and the sound would not have focus or center...
For the Tenor, most Rock, Jazz and Blues cats play on tips that are between .095" and .115, with the 2 most popular openings being
.105"(Link 7*) or .110" (Link 8)
I met Johnny Griffin who got his Metal Link 10 from Eddie "Lock-jaw" Davis,
down at the Village Vanguard, and he will play nothing else,
so every ones different...
Keep the Conn original and play some Classical on it.
Get a HR link in the facing of your choice and go from there.