ive seen 6th gen done lots of times. i had a 6th gen on my crx, its easy to do too. integra is also easy, same process, just difff parts. theres a guy on cardomain with a 91 hatch i think that has integra front and rear, go check it out http://www.cardomain.com/memberpage/444769
in my opinion that years ted doesnt look right, neither does the 6th gen, but im planning on doing a 5th gen front end on my 91. anyways all you need is...(well talk about the civic front end)

core support, hood, fenders, lights, bumper, hood latch

in a few easy steps.
-put teh new civic hood on, it will bolt right up. you may or may not have to cut a little off the underside so your windshield wipers wont rub
-remove radiator and everything on the front end
-drill out teh spotwelds in the core support and it will fall right down
-put the new core support up and align it with the hood so that it latches, make marks or do whatever u need to do to make sure u knwo where to weld
-weld the core support on, check to see if it latches etc.
-install headlights and bumper
-the next part is tricky. ul lhave to cut little section off of your fenders, and then using the new fenders, cut the front part off of them and place them up on the stock one and align it with the lights and bumper to where u want it. tack weld it in place and using body filler, fill in where they overlap to make it look smooth.

WALAHH. you will need to figure osmething out with the radiator though, it wont match the civic front , but i just used my old radiator and made a custom bracket thing for it, and it was fine.

thats basically it, they dont need to be done in that order, but do what you feel more comfortable and what easiest.