240 rear shock question - bump stop to unused piston travel distance?

After looking thru ~3 pages of results, I figured I'd just ask.

The question
Anyone know offhand how much travel is left in a standard size 240 rear shock when the bump stop is hit by the rear axle? In other words, pretend you load down your rear end to the point where the axle is touching the bump stop. How much piston travel is left for compression in a standard 240 rear shock?

The reason
Wanting to do the monroe 37349 shocks from a vanagon in the rear. Here're the specs:

Vanagon shock

Compressed Length 13.340"
Extended Length 20.940"
Travel Length 7.800"

Stock 240 shock:

Compressed Length 11.500"
Extended Length 17.500"
Travel Length 6.000"

The vanagon shocks have almost 2" more usable travel, but I'm worried that under heavy loading, the shock might bottom out before hitting the bump stop, reducing my usable compression distance.

I have Koni Sport shocks on the rear of my V8 car. Compressed is 11" The Vanagon shock might be to long {13.340}, The shorter compressed length would allow the car to sit lower with out bottoming out the skock

You should consider spacing the bump stops down.