I tried to run a IROC-Z 3.08 with a .72 T5 in my 235.....worked great as a 4 speed but wouldn't pull in 5th gear. I switched to an 88 Camaro 3.42 (62" wide) from behind a 2.8L V6 with a 28" tall tire and I cruise effortlessly at 70 mph in 5th@2000 rpms and still has plenty left. Can drop down to 45 mph in 5th gear and accelerate with traffic without needing a downshift. If I need to pull a trailer I can run at 65 mph in 4th gear at 2600 rpms. If most of your driving is at 55 mph a 3.55 or a 3.73 would also be good options.
Dave
