Whats SHould i get a RB25 or RB26?

Hey i need alot of help and as much info as i can get...im looking to get a 89-93 240sx Coupe and i was thinking a SR20 but my dream was always Skyline but i know i can't get the body but the engine i can...so if i go 240 i wanna go to the fullest...and i was wondering which one should i go 25 or 26? i know 26 i gotta get a 25 it a lil more stuff to do...I have a Honda civic hatch with a Gsr motor with a lil other things...i was thinking i can sell that car for a RB engine and some money left over for Labor and i have money on the side to pick up a Clean 240sx all stock....what do you think i should do?...i have a guy that Sells RBs but i gotta check which RBs He has an how much its gonna cost Dropped in and running...But for now what do you guys think i should do?...is this Dream Project Worth it? and this car is gonna be my last Car imma be playing with and then no more Car Imports.