several good fans out there. the dual ramchargers seem to be a popular choice for the tb crowd. Very inexpensive and will keep the car cool w/ ac on. I got mine from Gbody parts for around $120 if I remember correctly. Other vendors sell them too I'm sure.
Once you trim the side mounting tabs off, its a very nice snug fit. be sure and leave a 1/8" gap or so inbetween shroud and the fins. theres a number of effective ways to mount the fan, do a search for tons of writeups and pics.
There are also some very very good aluminum radiators custom built for our cars available from a number of the buick vendors, but their going to be a bit pricier (you get what you pay for), these imo, are going to be the better route to go over a gbody rad in most cases. I have been very happy with my fbody radiator conversion. I can post pics later if you'd like.
there may be some disagreements, but from my exp, a fbody radiator is going to outperform a 4 row core installed in our stockers everytime