A lot of building seems to boil down to this. You do it, then you do it again, and then again and again until eventually it's done. Very zen. If you mean $125 extra for a 4-stroke vs a 2-stroke (and a set of Replicraft plans), I'd say absolutely go with the 4-stroke! It's a fine investment in scale modeling. And really you don't need the Replicraft drawings for this build. You're already laid out some very respectable scale goals for this model.