Well I contacted a boddy that had some of these laying around - he didnt have an exact weight on them - but guesstimated they were between 400-550lbs (minus the transmission) depending on the engine and its contruction (aluminum head and aluminum block, or aluminum head and iron block).
There are several 3.0L and 3.4L engines from Toyota (gas and diesel) - from various models and years. Not sure what you were after - just the short block itself or looking for a swap. Tried to put information for possible sources as well.
6M-GE (Toyota Supra)
7M-GE/GTE (Toyota Supra)
2JZ-GE/GTE (Toyota Supra)
3VZ-FE (1988-1995 Toyota Camry, 4Runner, Pickup, T100, etc.)
1KD-FTV (Diesel - New)
5VZ-FE (1995-2004 Tacomas, Tundras, T100s, 4Runners, etc.)