Pop the wing off
Wing removal. It's only a few bolts at the bulkhead and a few at the breakfast IIRC and disconnecting the wires for the lights in the wing then it lifts right off. You'll save time and frustration by removing the wing then by performing the operation with it in place.
Not sure what you meant by...
do not want to remove the wing
want to do thru inside
because you can't remove the masters from the inside. Even easier still is after wing removal to pull the whole pedal assembly and remove/rebuild on the bench.
Most of all have fun!
Cheers
Walker
1968 Series IIA-"Ronnie"
88" SW, 2.25L Petrol, LHD