I may be off a little but here's what I found.

3G Hemi with steel block and exhaust manifolds around 485 pounds.
360 with steel block, heads and exhaust manifolds around 525-550 pounds.

So with aluminum heads on the 360 probably close? A lot of variables here since some 3Gs come with plastic intakes and some aluminum but it get's you in the ball park. You can also get a complete aluminum block for the 3G Hemi which really takes it down also.

Thanks a lot