Why the small map? Even in the 60's & 70's, the ranges of some of the main guns was more then 80. 80x80 in MBT is your basic 'chainsaws in a phone booth fight to the finish'. If you want to get to grips on how real world tactics translates into MBT tactics, you need more room. My usual minimum for MBT is 120x120. 160x160 is more reasonable, given that anything under 40 is pointblank range.
I could do an all infantry battle with only on-map mortars for support. Pick one of these wars and a side;
http://en.wikipedia.org/wiki/List_of...5%E2%80%931989
And we can get too it. I'll send an e-mail with slot choices, plus any other rules you want.