Is this your first build? >> If so and you don't want to gamble large sums of cash then consider the Infinity dynamic drivers.
If 8" is what you want look at the LS-0213 or LS0209.
http://www.scotronics.co.za/item_list.php?cat=68The TS parameters are not readily available but I have factory measured freq response curves for these drivers.
They are locally made and inexpensive (+- R500 a set)
And if you do the project from scratch you could measure the TS params. with speaker workshop.
I have used Infinity dynamics before and they are not to bad. In fact there are others on this forum that have also used them.
Visaton also has the Ws 20 E8. Maybe Noizyboy could get those for you or you could get them at RS electronics for a little more.
Well all the best with the planning.