The Mini was designed so in a bad smash the steering wheel would buckle forwards AWAY from the driver. If you lower it (apart from safety air bag considerations) you will lose that safety feature - and in a smash it will come back into your chest and probably kill you. Don't do it. Get a better/higher seat - or get rid of the car....... Your life is much more important than this.
thats so overly dramatic, the mini wasnt designed to cope with a crash at all, in the 1950's they didnt care a hoot, the mpi's only had airbags and door bars so it could scrape through the safety regs.
if you have a bad enough crash in a mini to fold the steering column away from you, youll be in a fair bit of trouble so i wouldnt worry about it.
wood and picket have been doing a mpi drop bracket for years,and they wouldnt sell something that would make your car dangerous, alot of people get rid of the airbag, how much do you think itll really help anyway?
if you want your car to be safer then just drive carefully, simple really
in short, crack on, get your car how you like it, if you worried about everything that could kill you you'd never do anything.
ps, just saw your profile picture,

lol ,sorry couldnt resist.