techumseh engine repair

Hi
I have an older Tecumseh H60 (6HP horizontal) engine. I had to pull the head gasket to change it, and several of the head bolts were rusted severely, so they got mangled upon removal.

Now you know since the head is flat, I just assumed when I took them out (and I was cursing the rusted ones anyway) that they were all the same, so I didn't pay any attention to what bolt went where.

I went to the outdoordistributors dot com web site and used their online parts diagram. It lists the following head bolts, (item 36 on their list) but does not list quantities or locations:
650697 5/16-18, 2 1/2
650695 same, 2 1/4, Grade 8
650694 same 2"

So, interestingly, the 1st and the 3rd numbers are about a buck each at outdoordistributors or jackssmallengines, but the middle one is two bucks. It was the only one listed as a Grade 8.

My questions to any Tecumseh expert:
1. Do they use all the same bolts, or do I need to measure the depth of each tapped hole in the cyl block?
2. If they are mixed, why?
3. Should I use the Grade 8 for all of them?
4. Why the price difference if they're all grade 8?,etc.

This engine if probably from the late 60s, an Ariens snowblower. I have no idea if it's original or they ever worked on it. It was running when I got it, but I had to take it apart for various reasons.

Thanks for any help,
John