Oh, man. I went through the same agony the first week I owned my 86... tried C clamps, vise grips, blocks of wood...
As Ken says, unbolt the scissors prop rod from the hood and you'll get that extra couple of millimeters you need.
This trick, though, is best done with a friend's help - if the hood drops while you're swapping the struts, you'll be in a world of hurt. Idiot me did the job myself because I was in a hurry - even though I know better. No harm done... this time. You could prop the hood with a stick, but that will just lead you to a false sense of security.
[RICHR]