You need 12 inch shocks to lower a V-Rod and still have enough clearance to ride the bike in the different conditions there are.Dyna models,just like the different V-Rod models,use different length shocks.The 2 best shocks to use on a V-Rod from a Dyna are the 06 DWG,and the Billet shocks that Harley sells.Any of the other Dyna takeoffs are not so great mainly because they are ugly as hell,just like Sportster shocks.You can have shocks shortened cheap.I buy mine used.The SE's I am having done will have a total of $130 invested.There is just no way in hell I would spend hundreds of dollars on a set of shocks unless they would blow me everytime I needed a blow job.
12 inchers will lower the rear appr 1 inch.The the front needs the same treatment.There are a few different ways to go about lowering the front.Like the stupid expensive aftermarket rear shocks,personally,I don't need all the fancy expensive emulator systems.I use the Progressive lowering kit and it works fine for me.