Need help IDing my 454

[77c10diesel]

I have an 89 Suburban 2500 2wd with the stock factory 454. I am looking for exhaust manifold gaskets for it and I am not sure what to get.
Summit racing lists Gen V, Gen IV, and Mark IV. I also need to know if it is square or round port.
I just have a small leak due to the right bank forward most bolt snapping off. (I got it this way) I want to remove the broken bolt and replace it, but want to have the gaskets on hand before I start.
Also, does any one know the size/tread/length of the bolt?
Thanks

[VileZambonie]

Most likely the small round gaskets. Pep boys stocks them.

[beastie_3]

I also suggest getting them local, that way if they are wrong, you can return them easier and faster, as well as bring in your old one to compare.