im sure theres no need for drilling/tapping the head/block. rad possibly?
theres bound to be a well known method of fitting, the ford gauges are among the nicest and have been fitted to tons of rst's, cossies ect. try motosport developments, burton power ect for fittings/adapters. ill be suprised if it ISNT the same thread/pitch as the oe w/temp sendor. its located on the front of the block nr the turbo area