Mark... a lot depends on what you're running for an engine and if you plan on hot rodding it! If you're using a V8, you'll definitely want to go with the WORLD CLASS (WC) T5 from the V8 Camaro.
This will need the S10 tailshaft plus modification of the speedo gear location. If you're using it behind a 6 cylinder the NONE WORLD CLASS (NWC) would probably do. You mentioned a .72 OD so you must be thinking of a S10 NWC T5 from a V6 application. In that case you wouldn't need the tailshaft.
The WC Camaro T5's are geared either 2.95, 1.94, 1.34, 1.0, .63 or 3.35, 1.93, 1.29,1.0,.63. With your 4.11, 30" diameter and a .63 overdrive you would be turning 1740 rpm at 60 MPH.
The NWC T5's have OD ratios of .72 from the V6's and .86 from the L4's. If your were running a 6 cylinder you would be turning 1989 at 60 MPH.
You need to be very careful to pick the correct T5 and gearing to match your engine. WC T5's in good shape are going from $500.-$750.USD. NWC T5's can be had from $150-$300 but you're buying a used unit from a salvage yard.
Just a suggestion....include a bit more information about your vehicle/engine and you will get more specific information. The "search" function will also yield a miriad of T5 information. I hope this helps.
http://community.webshots.com/user.Fla54Chevy3100
