74 is the Lotus mark or type number. All TCs and TCSes are type 74. I have a 72 TC, 74/2345.
Your car was made in October 1972, it is a 1973 model.
Yes to White with gold stripes.
It is most likely a TCS. Photos would help, particularly the dash. Easy way to tell, though, is to look at the rear
Suspension hub carrier, the aluminium piece to which springs etc. attach. If Left and Right are cast in the rear-facing sides, it's TC. How many speeds in the gearbox?
Brake modification sounds OK. The uprights and brakes (front) are straight out of the Triumph parts bin.
Sounds like you have a great car. Best of luck, keep us up to date!