Greg - Jack stands on these trucks are typically placed under the axle beam where the axle is bolted to the springs. Those are the best/safest support points. Resting the trucks weight on the springs themselves, other than where attached to the axles, can cause damage to the springs in addition to being a collapse hazard. Definitely block your rear wheels, both in front and behind, to prevent movement as well as setting the parking brake.
Torque specs for the flywheel and clutch pressure plate can be found in the
1954 Chevrolet Truck Shop Manual as they are the same as for your 1955.1 1st Series truck. Flywheel to crankshaft bolt torque should be 50-65 ft lbs with a torque wrench. Pressure plate mounting bolts should be torqued to 25-30 ft lbs. again with your handy torque wrench.
