should i keep my carburetor or buy this one?

It would be for a 68 Dart

If your wallet opens wide enough, get this one for your '68 (seller has a "make offer" option). The BBS 6026 is a real nice-running carb that'll go right on your '68 even if it had a Holley to start with. Only hookup hurdle is front rather than side fuel inlet; good excuse to do the Fuel line mod.