well, strictly speaking there is no actual sequence, but whatever is within reason.
Personally, I would first install the brakes, servo and lines, then the steering rack, speedo cable, and then I would go with the engine and gearbox, front crossmember, rear axle is already on so you dont need to remove it in order to put the fuel tank back on.
Then the wiring, as you might need to move it around various engine components and hoses when fitting if you have it there before the engine goes in.
Then windscreens, dashboard and interior would go next, exhausts and trim.
By the way, make sure you install the front windscreen on before you install the dashboard, otherwise you will have a hard time puting in the lower section of the screen rubber.
Also make sure you install the heater box and the interior floor liner in as well, before you put the dashboard.
I'm sure you will find your way through it
Oh, and it would be better - easier - if you change the gearbox oil before you mount it on the car, when its nice and level and easily accessible