Another alternative is a prop shaft extension. Fox makes them in 1/2" and 3/4" and for 1/4-28 thread and 5/16-24 thread crankshafts, so if your engine's shaft has one of those threads you could just leave the engine where it is and move the propeller forward.

Moving the engine forward will move your center of gravity forward too. THis may be a good or a bad thing, depending on how your airplane is balanced. If it was tail heavy to begin with, moving the engine forward will help. If it was right, or if it was nose heavy and you had to add weight to the tail, moving the engine forward will make things worse.