Dan Heath said: You can always add the spacers later, it is no big thing other than adding the inches to the cowling.
I added spacers to my friends finished KR2, which moved the engine and cowling forward of course. It is a big deal to remake the cowling and trying to make all the angles line up with the fuselage. Just imagine the curvature of the side of the fuselage that curves around onto or into the engine cowling, this look TOTALLY CHANGES when you move the engine and cowling forward. If you want your plane to look good this requires more time and effort than it originally did, trust me I have been there. If you don't care what your plane looks like then yes just add to the rear of the exhising cowling which is still not that easy of a task and let it go. I highly recommend that you place your engine where it will stay and make your cowling the way it will stay also from the very beginning. Re do's are very time consuming and a huge pain in the rear end. Anyone who has made this change knows what I am talking about if they took the time to blend in all the angles and make it look good. Larry H.