like most models of cars, it's not just the engine loom that will be different. If you're willing to strip both cars; carpet, dash, everything, yes it can be done quite quickly. You will still need to do some cutting of the loom, whether that may be engine engine bay dash body etc. The other way is to start cutting, but most people do this who have done it before or have wiring diagrams.
I can tell you first hand, once you have found one problem another will pop up.
Could always sell the neo for 1-2g and put your manual into the 34 fronted s1. Then later on wire in a stand alone to tune.