Transmission swap

Hi all, I am really considering this spring/summer to swap
transmissions from my 85 2m4 5 speed 180K miles to my 85 GT 4 speed
70K miles.

My questions are I guess will the clutch have to be changed out as
well as I see the Fiero Store sells different clutches for each.

Also what other surprises should I expect.
I drive the GT most of the time and do not like the 4 speed / reverse
layout also since the 5 speed at 65 mph runs at 500 rpm's less I
figure I will get better gas milage.

I know I will have to changer the shifters in the console as well and
rewire the back up lights as the 4 speed switch is in the shifter
console and the 5 speed switch is on the transmission.
Thanks
Hank