Flexible brake hose replacement whilst critical, isn't a particularly difficult job to undertake and thankfully, the correct fitment or otherwise, is easy to check after the repair has been done.
The main issues around replacement:
1) Seized metal brake pipe unions (see 4)
2) Seized bleed nipples (best to make sure all four come loose before proceeding).
3) Caution when screwing in brake unions; don't use the brake pipe spanner until you first screw the union threads in by hand 2 - 3 turns, they can easily cross thread and have to be exactly square on to engage.
4) The brakes can sometimes be a pain to bleed after the system has fully drained of fluid. You will need at least 2 litres of DOT4.
5) The nature of this job
MAY lead to one or more metal brake pipes requiring replacement
IF unions round. A pair of Vise Grip (locking pliers) is an almost obligatory tool in the removal of stubborn seized brake pipe unions.
6) Personally, I am not a fan of aftermarket, so called 'performance' braided hoses. I would stick with genuine original replacements or quality brands.
7) Avoid twists in the hoses and don't crimp.

When bleeding, a pressure bleeder is preferred but if this is not possible, use controlled depressions on the pedal and good half turns (fully open bleed nipples) to avoid resistance when bleeding.
9) Top up the fluid regularly (under the speedo binnacle, pull up from the rear) to avoid drawing in air (otherwise you will have to start all over again)
10) Bleed furthest away from the master cylinder first, working your way to the closest. Run 250ml through each cylinder/calliper. You might want to bleed the clutch slave cylinder at the same time (it uses the same reservoir). This is positioned on the top N/S of the gearbox bell housing.
Has the job been done correctly?
With the engine running, get someone to press reasonable hard on the brake pedal whilst visually inspecting the brake pipe connections.
There shouldn't be any leaks
Take time to have a good feel of the brake pedal before the repair so you can compare 'before to after' it shouldn't feel any different or should I say, it should feel at least as good.
Move the steering lock to lock and check the tyre to hose and hose to spring clearance on the fronts.
Finally...Road Test...see if it pulls up straight and with a good pedal (same or better than it was)
If it does pull or the brake travel is worse than it was, it will need further bleeding.
Martin