On my 68 Coronet I just use stock passenger car
mufflers. They sound great and have that back in the day sound. The lengths on them are about 18" . I believe the ones I have are Maremount. The performance is good too. My exhaust is 2". Check them out for 2.5".
The good thing about them is that they last a long time. Going on 5 years and still good.
I had a set previously that lasted 13 years.
Got tired of replacing turbos every 2-3 years because they would rot out. That's why I went with regular muffler.