Go to Chevy Talk and look on their forums. Either look under the 48 chevy section or the 55-57 I think it is... I was looking into it as well and they said there are kits or something like that for these cars. I looked into it but a ton of work but worth it. I am not going to do it because my car will not have AC so I need the vent windows to bring in some air. What you do if you decide to just keep them is just tint your windows dark, have the trim around the vent glass black and everything else and it will not be so noticable when they are closed. I have a 48 Chevy Coupe and I plan on tubbing the rear out with around 16.5 inch wide tires, Center Line Convo Pro Series 00 rims, ford explorer rear end with disks in the front and rear, I have a 79 Camaro Z 28 front end on it, it will be gloss black with either metallic blue flames (just out lined) or ghost flames in a pearl blue. I plan to put a big block in it and a 4 bar in the rear. That's all I have planned for now, who knows what happens between now and when it gets done because that right there will be TONS of money and take a lot of time. I will also have ALL white interior and making my own custom door panels and all and would like to make the flame job on the outside come through and have the flames on the door panels. There's a huge list of course but you get the idea. If you guys need or wan't more info on JUST 48's then go to www.chevytalk.com or www.my48chevy.com The guy that owns my48chevy.com is really nice and will help you out a TON and has parts for sale on his site as well.
Post some pics up of your rides if you can. Nice to see some more people on here with the same style and year car as mine.