Gentlemen: Wanting to build an A Frame crane with fixed feet, non rotational, using 10.750" steel pipe, .500 wall , 40 ft. tall,with a 4 sheave head for 3/4" cable approx. 34 " width at top using 3" solid shaft for sheave support run through both legs and head tied as a unit with 1/4" steel plate boxed around the head of both pipes and legs spread apart at the base of 10ft., two 1" cables will attach tip of boom to a stationary point approx. 70 ft to the rear of boom and the boom operated at a 10 ft radius from bottom of feet. Steel is 36 KSI with a 'K' frame midpoint approx. 15ft down from tip of 8" schedule 40 pipe, all fully welded full penetration. Safety factor of 2 to 1. Can someone tell me what the theoretical capacity would be?