RLeo, you make a good case for re-cutting my driveshafts when and if I ever find a 5-speed.
No driveline buzz that I have heard so far. Don't jinx me, I am still listening hard, and I have had exactly a week with this new beast. The first time I took it on the highway, it seemed noisy; subsequent trips make me think I was just paranoid, worried about the thing falling out. It seems very quiet in all the gears except lugging it up a hill you can hear the gears complaining. I have spent a lot of time in 3d and 4th, less in 1 and 2.
I was expecting vibration based on the testimonies here, but if anything it seems quieter than before. I had the driveline professionally cut and balanced, and put in the alternate 240 trans crossmember which fit like a charm, using a new 300 rear mount (much thicker than the 240). New flexdisks, fresh ATF of course.
I also have the 240 flywheel and did nothing to balance. I could not see any matchmarks on anything but the disc attached to the torque converter, so we just put the thing in where the holes matched, meaning any one of twelve possibilities!
It idles smoothly, a tad higher obviously, and not a whisper of anything suggesting major imbalance. The long term results will hopefully bear out what others have found about using the smaller flywheel.
By the way, my tech found me a nice wooden (zebrano) shift knob that is not only pleasanter than stock, it is also shorter by 1.5", shortening the throw and the height above the console. Any interest, I'll find out who and where. I think it was $75 or so. Pricey for frills, but it helps convince my family that my 22 year old car is not just a beater! I don't understand them....