Why don't you cut off the end, take it to muffler shop and have them expand it, then you can trim section off the remains part under car and slip the turn down on, sorta like a tip.

ok ill bite, since you chose the non-factory tipped look (i did too) the slash/diagonal cut would not have been my choice.
the single pipe slash looks oem for many cars to me. i like the chrome tips too but they are kinda hokie.
that tough, high horsepower and menacing look (to me) has to be square cut turndowns and dont hide them too much too.
ill post a side shot for you later in my ( ricky's cha-ching-cheapo) build.
yes, i do know what is said about opinions
copper

The tail pipes are probably designed to fit the lower bumper location of the 67-69s. They do look like they are sticking out too far since the 70 had the bumper up a lot higher.

I bought TTi tailpipes for my 69 , HUGE waste of money , they didn't even remotely fit in the factory location , I had the shop that made my headpipes cut and reweld them to get them to fit in the stock location ... that may not matter on your car Joe ? you could always do as mentioned and have the pipes shortened ?

I bought the TTI exhaust for my 69 GTS but did not buy the tailpipes because I had NOS ones. The mufflers they sell had rear openings too big to I had to use reducers. The factory tailpipes are just 1-3/4".