Well, there's about two ways to go about this. You can either have your head rechambered for the new stroke or run spacers to move the head and/ or cylinder up. It is highly recommended to have the cylinder ported to match the new stroke.
reporting is almost a must for that much stroke. seems to me like the spacer would f*ck the tuning all up.
i think you've also got to trench the case for a 4 over.