New 5-speed kits for A-bodies

They quoted me a kit for about $3600. My Duster is an original manual shift car. Keisler does more modifications to the tranny for easier fit. Classic requires cutting the stock crossmember for clearance and does not modify the trans. I've heard of problem shifting into 3rd above 6000 with the Tremec. I'm planning to go with the Richmond Super Street 5 speed.