It would need to have the case clearanced, It's not too bad with a 78mm. You can do it yourself. You will also need to check the crank to cam clearance. A set of stroker rods will be needed, that will add a little to the cost of the engine build but not too much.
There are other things you will need for the build up but they are thing we already talked about and will work for either 69 stroke or 78.
Geoff.