I did the front disc brakes on my 2002 e825 and in Pacific Beach. I posted pics and about it in my build thread( Just purchased 2002 e825-4 where to start rejuvenation? - #23 by dougl ). Put Leaf Gen4 batteries in mine( Nissan Leaf Gen 4 battery conversion ).
I would hold off on the R4F motor as the stock 5hp does pretty well unless you really need the extra 2HP from an upgraded motor. IIRC they have similar highend RPM limits so it won’t get you more speed, just get you there a bit faster.