rolls are sized in 2 feet shorter than you need or twice as much.
no in between.

engine, to back of muffler at rear wheel.  Full exhaust.

I have never wrapped a pipe....so I can't tell you from experience - but I can offer a calculated guess.

The OD of the pipe is 2".  Multiply this by 3.14 to get the circumference....which is going to be 6.28 inches.  Since you are going to be going at a bit of a diagonal....I would count on about 6.5 inches of length for each lap around the pipe.

I would also suspect that the overlap would be such that you would have a double layer everywhere.....a 2" wide band of tape would only progress 1" for each lap around.  Based on this you would need 6.5 inches of length for every 1" of pipe length.  (For different widths you will have to adjust this number).  I supposed you can fudge this number a bit by spreading out the wrap so it does not have a full 2 layers everywhere.....but still overlaps a bit.

I removed the stock muffler at the joint, and slid on a 1.75 Thrush glass pack.  I am going to wrap the exhaust from the cylinder head all the way back.

Usually there are 2 sizes.
most here wrap just the header and it takes the shorter roll.
you'll probably need the longer roll

I used almost 20ft to wrap my exhaust setup. It's about 30" of total pipe wrapped. Best bet is to buy the longer roll having extra never hurt anyone. Coming up short will just make you mad and nobody wants to buy another 15' roll to splice in 2 feet of wrap!

For me I always start at the end of the exhaust and work back to the header. Just looks cleaner having whatever clamping system at the header than the end. And wet the wrap and when I say wet completely submerge it in water till it's soaked. It will smoke like hell until it dries out but it's way way easier to pull tight when wrapping the bends  

HA! I have both those answers. BUT,  I'm not telling until someone explains women.