http://acurazine.com/forums/performa...eights-913909/
Engine assemblies minus:
Intake manifold
Exhaust manifolds
EGR valve
Flywheel
Engine mounts
Wire harness
All accessories
J37A2: 298 lbs
J35A8: 296 lbs
For the LS I searched LS1 and it made a lot of various weights ranging from 350 to 400 depending. The 400 was without the clutch and manifolds but wet weight, intake, accessories ready to drop in. Its not as drastic a difference as you think. As far as pricing.... I am willing to bet anything LS related would be cheaper than anything J series related from what I'm seeing on the acura / Honda sites. Plus the reliability and functionality / tunability of the LS.... its just a better swap. In every regard except being unique.