5 or 6 speed conversion

I'm thinking about doing a transmission swap in my 69 valiant. I'm almost done my small block 408 stroker, and I'm thinking about putting in 5 or 6 speed. I came across a website americanpowertrain.com and they specialize in tremec conversions.
Anyone out there done a conversion with Keisler or a tremec?
Anyone have any suggestions or info?