Well, if your engine stand is anything like the ones I've used, they bolt into the same holes that the bellhousing bolts to at the rear of the engine block. There are 6 holes and 4 arms on the stand. I use the holes at 3 o'clock, 9 o'clock and also the ones at 11 and 1 o'clock or you can use the ones at 10 and 2 o'clock.
The bolts to use are the same diameter and thread as those that fasten the bellhousing....just longer. I think they're 3/8 x 16 or something close to that.
Just take one of the bellhousing bolts to a local hardware store (or rummage thru the spares box) until you find some that are long enough to pass thru the arms on the stand and into the back of the motor...about 4 inches.
There are some pics on this page
http://www.chevyasylum.com/85monte/85monte10.html that show the 406 motor for my 85 Monte Carlo on a stand. You can kinda get an idea of how it's bolted up from them.
Good luck