as a general statement, you should choose points as high as possible on two opposite corners of the engine. to make that specific, using a manifold bolt would be suitable for one corner, and find a suitable hole (5/16" minimum) on the opposite corner.
haven't done many of the small 6s myself, but on the 300 i would often use the power steering bracket for my forward connection and on the rear i would remove one of the block-to-bellhousing bolts, and put it in its hole from the other side (it was a through hole), and lift the engine from those 2 points. note that i was pulling engines in this way without any unneeded disassembly, sometimes even leaving the fan, carb, and more attached to the engine, thus making many better lifting points unaccessible.
note that a load leveling bar will make the job much easier (but i have yet to get one)
as for removing the head first, it shouldn't be necessary, but its no harm if you do.
for mounting to the stand, it should be 7/16" bolts IIRC. pull one of the block to bellhousing bolts to find out. length depends on your stand, but i would suggest they be long enough to have 1/2 to 3/4 of an inch threaded into the block.