When I built up my most recent 261 a couple of years ago, I weighed all of the parts as it went together. The total weight, with bellhousing, flywheel, clutch, and transmission was 687 pounds. Here is a
summary table. The flywheel and pressure plate are aluminum; the transmission is an iron 1958 passenger 3-speed.
As Jerry says, you need a good engine stand, with enough wheelbase and track to keep the center of gravity well within the wheel footprint. I started with a three-wheel stand that was fine for a small-block V-8 and nearly had a tip-over when I tried to rotate just the short block of the 261. I bought the best four-wheel stand that Cummins Tool sells, which I believe is similar to Harbor Freight's version.
Hoyt
