betzjr66 I have a couple of questions. What is the power output on your BBC? What tires are you running, Street autocross, slicks? This question is most important, what are you going to do with the car? Street driving and Shows? autocross and roadracing, Drag racing, alittle of all this? Here is the issues. You have not said which trans you have. The one that has been out for the last 15+years has a tork and HP rating of 450HP and 450ft pounds of torque. For normal street driving with street tires this trans SHOULD be no problem and holdup. The gears inside are cut a 22 degrees to keep the trans quiet and keep noise down. The new Super street trans has straight cut gears and a 600 HP and torque rating. I'm sure that you BBC is maken 500+ ft of tork. I run 2 different transmissions. I have a 6spd Richmond for street with the overdrive. The first gear is 3.25, what a waste with 3.31 rearend gears I never use it. It's 1" longer for the trans mount location. It only has a 450/450 rating. I don't beat on this trans and ONLY run BFG street tires because they have poor traction on the street over other tires. I race with a G-Force 5 spd. The externals are the same as a richmond 5 spd but this trans is good for 1000 HP and torque. It's a semiclutchless 5 spd. It is also about twice the price as the cheaper Richmond 5 spd. I am looking at the superstreet 5 spd with the 2.87 first gear and overdrive 5th gear. This is the one that would BEST fit you over all needs. IMO You will not hear the straight gears when driving if you have side pipes.
I like and run both transmissions in my car, I also KNOW there limitations.
Rick L.