I have an 86 conv. (4+3) The engine was rebuilt and modified for horsepower years ago, however I've put less than a 1000 miles on it due to a variety a reasons, namely I cant drive it more than 10 miles before the oil temp slowly creeps up to redline temp (265F). I've gotten all sorts of theories and answers and nothing helped including running 15-50 mobile 1 and replacing the sensor. Any ideas? I want to drive the car more but can't, especially with this strange problem. And yes it started running hot after the engine rebuild. Help.

well first let's ask how do you know the oil is too hot...other then what the gauge tells you ...have you gone to the ridiculous lenght of getting the engine hot ( too hot according the the gauge) and then carefully taking a sample of oil and measuring the temp with a meat prob thermometer or a candy thermometer??..on to more reasonable....how hot is the water getting when the oil overheats??
have you checked the oil cooler for plugging?? Say disconnect a line and blow compressed air through it??... What is your oil preasure reading ??? does it go down as the oil gets hot???

The guage is my indicator. When I reduce my RPMs and speed the oil temp does come down (very little), so it makes sense the guage is correct. I have not been able to get a termometer with a high enough range to test the oil. Also I cant extract enough oil to do a compreshensive test. I really don't want to burn myself disconnecting lines on a superheated car.
The water temp cycles through it's normal temp from about 220 and then goes down. (it had a 180 and 195 thermostat in it) This doesn't affect the oil temp. Outside air temp and RPMs affect the oil temp.
It would appear the car has a hi-po oil pump in it. OP is 76-80psi all the time. Someone pointed out the car doesn't have a Hi-po oil PAN and it may be sucking the oil dry. Killabrew said to put 15-50W mobile 1 in it. No change. Oil is clean with less than 1Kmiles on it.
Havent checked the oil cooler or lines. Don't know if this has one as they werent stock.

well the first thing you really need to establish is that the gauge is acurate...it may go down when RPMs drop ..but it could be reading high to begin with ...my gauge doesn't even work ..doesn't mean my oil is cold.... so if you really want to find out ..buy one of these so you can take a hot oil sample ( PAIN FREE) http://www.fumotovalve.com/

you can find them on ebay sometimes too ...and as for measuring the oil temp ..a candy thermometer will work just fine ...one like this http://cgi.ebay.com/CANDY-DEEP-FRY-THERMOMETER-BAKERS-SECRET-NEW_W0QQitemZ4469678863QQcategoryZ43421QQrdZ1QQcmd ZViewItem just take a sample and float the thermometer in it ...

have you considered installing an oil cooler ?? being that you don't have one ??? here is a site were a guy did it ...a lot of other usefule stuff too ...http://www.xse.com/leres/ss/oilcooler.html