I just bought a 88 reliant today and when test driving it i noticed the temperature gage would fluctuate based on my foot pressure to the gas pedal. what is that all about? should i be worried about a cracked or leaking head gasket? ugh

Yes reliants while a good car did have some problems with head gaskets. and this would be an indication of a head gasket problem check the oil is there water in it the oil will look milky. is there any oil in the coolant? is the car blowing a lot of white smoke all of these symptoms can be indicators of a blown head gasket.
the fluctuation in the temperature could also be a bad water pump is the vehicle getting good flow through the coolant system?
hope this helps

Sounds like u have a leaking head gasket, the more power u apply the quicker it leaks as the pressure goes up in the combustion chamber, this puts combustion gases into the cooling system and makes the engine run hot, gas does not cool the engine..