Well if you like metal work, the change from pistol to straight grip should be fairly simple for you. You need to extend the trigger guard, bend the top and bottom tang up and re-drill and re-tap the rear pin. Why so many changes? Well, short trigger guards look poor on a long straight grip. The angle of the tang needs to be higher so the comb does not look three inches high and like a bird's beak when you raise the comb. Change the tangs and the threads will not work on the rear screw/pin.
Now I know that you can skip all the above steps but if you can handle the metal work easily your final product will be much nicer if you do make the changes. The above steps are well coverd in Steven Hughes' book on fine doubles and custom stocking them. Easy find on E-bay for just a few dollars and worth the read.
