You wrote:

>> 1. Is it possible to make the 3.5X6.5X10 port a slot, instead?
>> Say, 10WX3.5HX6.5D?

Yes, that will work. You can change port shape slightly and expect it to act pretty similar to another having the same cross-section area and length.

>> 2. I have 2 sets of 1.6k Eminence crossovers, one stock for the
>> PSD-2002's and the other with the 10uF removed for the JBL
>> 2226J/3677s combo. Do I have the parts I need to make an
>> 800Hz X-over?

No. You'll need to get parts to make an 800Hz crossover, because values for the 1600Hz filter are different.

>> Is there a Pi schematic for an 800 Hz X-over?

Yes, and I'll send it to you right now.

>> Should I just get the Altec X-over on E-bay?

It is an option, sure.

>> 3. I saw somewhere that the Altec horns were designed to be in
>> free air,not in the box. True? Is it okay to have it in a three-sided
>> box as long as it's not the same box as the woofer? I'm thinking
>> of the way LaScala's are built with the horn and crossover open
>> to the back and separate from the bass reflex boss.

Actually, most horns are improved by mounting on a baffle, because they are then radiating into halfspace instead of freespace. I think that the Altec's probably don't need baffle mounting, certainly not if crossed over high. That makes horn placement a matter of aesthetics, really. But I wouldn't hesitate to baffle mount or to put the horns in a cabinet.

Take care!

Wayne