You will need to invest in a really good (ie not a w58) gearbox to cope with the instant torque off the line, something like an R154 or a V160. (neither of which comes cheap)
Everything else depends on what car its going into.
Its a $5k conversion for a 2jzge into a ma61, then expect to pay another $5-6K (more if you buy a good gearbox) to do all the mods and get all the parts required to run that sucker properly.
Instead i have bought another car with more power with the money i would have spent just on the mods to get the blower working.
But your looking at about 7-8psi 400nm of torque throughout the rev band!