Do you think ill have as much problems as you have had, if i use stock exhaust manifolds and a single exhaust line? I still cant believe you had to mess with the trans tunnel so much. Still, im thinking a 5 speed is worth it.
This is a big job with lots of little modifications as I go along. There is another FABO member that I've kept in touch with and we have been sharing our experiences. He had to modify the rear crossmember and tranny tunnel as well. I have not seen pictures of his work but I think it is very similar. He said they did weld some extra sheet metal which is what I may do today to make things look cleaner, even though I think it is strong enough the way it is.
As to your question of having a single exhaust line and stock manifolds...you should go dual exhaust for sure. I don't think it would be a big deal to just have a muffler shop bend up the pipes for you. I would modify the transmission mount so you can tuck the passenger side pipe up into the chassis more if you plan you use a 904 or 727 with dual exhaust.
The 5-speed tremec TKO-500 transmission is an awesome transmission. The Keisler kit for the early a-body has lots of problems as you can see. Once the transmission is in and the car is running I know for a fact it will have been the best improvement that I could have ever made to the car besides new disc brakes. People that I have talked to absolutely love the 5-speed. It is a whole new car afterwards. For me, I know it will be well worth all the headaches and hard work in the end. Plus I have learned so much over the past year and believe this is what hot rodding is all about. Trial and error. I say go for it on the 5-speed and be prepared for some hang ups along the way. Ramble Ramble