low power tube amp

yes, i also think the 829 amp is something special.
It had a great review by wall of sound in canada.

I compared it side by side with simaudio moon's flagship integrated amp, and the difference was not even subtle. The 829 had texture and detail way beyond simaudio's

I would ask your amplifier builder once you narrow down your speaker selection as you have a unicorn for an amplifier.   I would also ask him how he built at kt88 SET amplifier. In my 35 years of owning various tube gear have never seen a KT88 SET.   Would definitely audition amplifier and speakers hooked up together.   Power needs are gonna be dependent on material, room size, volume levels etc.   Most likely you have a SEP (pentode not triode) amplifier.

Hi timber77,
Yes,  the distinction between SET  and SEP  was explained earlier in this thread. The actual tube in this amplifier is an 829b. 
Charles 

The low wattage won't damage your speakers.  The only question is whether or not you're getting enough level and do they sound good.  If not and you love tubes, check out:

http://www.tubes4hifi.com/bob.htm#ST120

If the speaker choice is still open, consider some speakers that are more efficient (that is if you are planning to keep the amplifier).

I would be on the lookout for something in the 93-96db efficiency range; generally speaking its not a good idea to push a single-ended amplifier very hard (and FWIW, this amp poses no threat to the proposed speakers).