Sell your 805's and get the Reference 3A MM Da Capo's. They sound simply spectaculare for the price and are very efficient. I believe you can find a pair of used ones for a little less than $2,000.
Just for the record, an 845 is not a "low powered SET amp".
Because of the ~25wpc it brings to the party, most SET adherents would consider it a muscle amp. This gives you real versatility, and greatly opens up your options for speaker matching. In a relatively small room like yours, you should be able to drive almost any moderately efficient speaker, although you still need to watch for unfriendly loads. With a relatively efficient and refined speaker like the da Capo you may want to consider a lower powered design.
Good luck and have fun.
You are absolutely correct on all the points you raised. My Cayin SET m'blocs using 845 op tubes are rated at 28wpc and they are very happily matched to the Spica TC60s which I bought used at low cost. I don't know the efficiency of the Spicas; unfortunately the manufacturer has gone away, so such information are not available for this forum discussion. I think the sensibility might be around 87/88 dB/w/m. Spica owners reading this may want to join in with the correct information. The 845s at 28w definitely open up a lot of good speaker options, the likes of TC60 in the used market. Sorry am not able to advise on the da Capo, but Cowman is right about exercising care matching SETs with higher relative efficiency speakers.
Don't give up!