How to thread on TKO600, need advice.

Looks like you've been doing your homework.

Out of curiosity, why did you choose American Powertrain's TKO 600 over SST's? Also, which gear set did you choose?

Doesn't American Powertrain have the clutch and brake pedals? Check with them. I thought they had it as part of their kit. If not, you'd might want to check with Brewer's Performance or maybe even Passon Performance for pedals.

Also, to convert your steering column from column shift to floor shift you might want to pick up one of these: Mancini Racing Steering Column Collar