Smoky engine? how bad? could be okay for years, could not. Mine got that way and then started knocking, so I replaced the engine...
Stretch moves either your front axle forward or your rear axle backwards, or both, thus stretching your wheelbase. IIRC, with the waggy springs, the pin is offset (not centered between the spring eyes) and that is where your stretch comes from. <-Not 100% sure that's what I've read about waggy springs, but I'm like 90% sure
The shackle reversal does exactly as the name implies, moves the shackles to the reverse side of the spring. This will offer benefits of ride quality, and maybe offroad ability (again, not sure) because when your tire hits a bump, it moves rearward (the natural direction it wants to) vs stock, where it wants to move forward
Hope that helps some
"Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life."
1990 White YJ TBI350, SM465, NP231, SOA, RE 1.5" SOA springs, Ford 8.8, D30, 4.10's, JBConversions SYE, XJ shaft, Bilstein 5150s, jb4x4 steering, MORE SS brakelines, 35x12.50 15 MT's, '95 YJ Brake Booster, '78 Grand Marquis MC, ZJ Prop. Valve