Quick question about replacing Tach and indicators

I am unsure if this is the right thread to ask but I am considering replacing the old Tachometer and Indicators on my 1982 Xj650 maxim. I recently replaced my speedometer and had to run new wires to a new fuse box as there was no existing wiring for me to splice into. My question is, if I replace the Indicator lights (Oil light, High beam light etc.) and the tachometer, can I just cut the existing wiring and splice them together with the new wires and have it work properly? Also if not what struggles should I expect?

 

I would refer to the "Atari delete" Threads as there is a bit of re-wiring related to adding new speedo's , tachs and their associated indicator lights.
From my recent experience of adding a new fuse block , it drastically affects the starter circuit and amount of power being delivered to the coils. be sure that at the TCI there isnt too much voltage drop ie. below 9.5V as any less delivered to the coils will result in non -ignition on the spark plugs.