Engine A frame

Hi all,
I'm measuring up my A frame engine lighting frame to lift my chev 350 in to my boat, my question is how wide does the bottom need to be
I need a hight of 3mtrs I am thinking 2mtrs either side of centre making frame 4mtrs wide at the bottom but it looks real wide ?

 

You only need enough to get everything to clear, whatever this works out to be. Figure a hefty load, particularly if it's oiled up and has the trans attached, so at least 700 pounds (325 kg). Some 2x6's with a doubled up 2x6 as the cross beam will work. Attach some diagonal braces, so it can't wrack as you hoist. Also allow for the hoist or come-along, so you don't come up short. The bottom of the support legs don't have to have a wide base, but if the legs "splay" a bit, it'll be more stable, especially if you have to swing, wiggle and "convince" the engine to move where you want in the process.