Cluster removal should take about 15mins if you know how to operate a screwdriver and can follow instructions given in DIY's here at SAU.
ps. a search in "drivetrain and transmission" is a good idea
It has been cleared up for several years.
This is fine to do providing you follow the procedure in the manual. Pump the brake pedal etc.
As to whether you are comfortable running it on a 2WD dyno with a mechanical linkage still in place is the only questionable thing about doing this.
Nistune board in that ecu would be the easiest way to go but there are a number of options for aftermarket engine management available if you wish to go a little further with the car.