I once used a length of 2" pipe across the front fenders where the hood shuts against it--drilled a hole in the center of the pipe for a threaded rod and made it into an eye bolt,to hook a chain to it,bolted the chain to the engine,and tighten the nut on the rod to lift up on the engine..
A 4x4 wood post would likely be strong enough too,if you have no pipe --just watch the fenders for any sign of stress while you tighten up the nut..my inner fenders are swiss cheese and the fenders aren't much better,but they didn't buckle any lifting a 350 up that way..
This leaves underneath the truck "open",then your not having the jack and 2x4's right in your way..put some blocks between the motor and frame for safety so if the "lift" decided to slip,you wont get anything crushed..