Originally Posted by vstech

... as finicky as the 87 heads are, ANY issue with cooling needs to be addressed instantly. if you have a KNOWN leak, and you have not addressed it, you are likely running with air pockets in the very weak very soft head... and likely it's blown apart. the 120 pegging is a very bad sign of possible exhaust dumping into the coolant.
where are you located? a member may be nearby to assist the diagnosis.