91 grand prix gtp rad question

Last thursday i bought a 91 gtp with a blown tranny. The car came with a motor and tranny out of a 95 gtp with under 100k ok them so i swapped the motors over the weekend and nearlyhave the new motor all hooked up but on the rad i have an empty threaded hole. it is in the top corner drivers side on the motor side of the rad and i was just wondering if anyone knew what should be connected to this hole i have all the tranny lines hooked up and the rad hoses so im thinking its a pressure relief valve and the valve is missing? if anyone has any ideas it would be greatly appreciated.

Also the drivers side window only goes up and down about a three quarters of an inch and the passengers side doesnt move at all and i was wondering if there was any way to test the motors or see if its the controls that are screwed up.

And it is the 3.4 motor

I was also wondering if this model year has the speed limiter or not? it has a rev limiter so i assume it also has the speed limiter? and if it does have the speed limiter what would it be set at? 160km/h?