How wide is that shop? Looks like 28'
I agree with others, dont hang anything from the trusses. Your trusses werent designed and engineered for that. Do you have any of the specs of the trusses, and what loading design they were built for? Everytime I have ordered trusses, They ask alot of questions, like what roofing material is gonna be, any ceiling attached to the underside, etc. They really build them about as light as they can get away with.
I'd get a 28' beam, sufficient to span the width of the shop, mount on two columns, then hang the hoist from that. Would you have a way to hoist and set a 500# steel beam in place?
What is the specs of that hoist? What does 750/1500# capacity mean?
Assuming its a 1500# capacity, and 28' span.....you would need a minimum of a W6x25, W8x21, W10x19 for a beam.
IF its only a 750# hoist spanning the 28'.....you would need a minimum of a w5x19, w6x15, w8x13, w10x12, s6x17.25. s7x15.3 beam.