Is this something you are going to buy new? The SW can be specified to standard (roughly D3) in the order.

Have you been fit recently by a Titleist fitter for +2 inches? That is uncommon. Being +2 inches, this would need to be a custom order to Titleist and they adjust SW based on the customer order when specified. They would try to get to a SW with a lighter head on a shaft that long.

Each 1/2 inch of length will increase the swingweight by 3 points, i.e., D3 to D6. Lengthening by 2 inches would get you way up to the E's. I'd imagine a player needing a club that much longer would have significantly bigger grips. Each 5 gram increase of grip weight will decrease swingweight by 1 point. Bottom line in getting a club that much longer is to see a club fitter. But I've played with former NBA and college players who had gotten clubs made that much longer that were still playable.