[Sca-cooks] Long Pepper Substitute?

[lilinah at earthlink.net]

None of the spice vendors where i live have long pepper. I can order
it from Seattle for over $5 per ounce from
http://www.worldspice.com
but i wanted to mix up a batch of Poudre Forte this week and it calls
for black pepper, long pepper, and some other fairly common spices.

What i'm wondering, vainly perhaps, is can i substitute cubeb and/or
grains of paradise for the long pepper?
I know it won't taste quite the same, but would it be radically different?
Or is there something else i should use?

Anahita