You can cheat the column over if it works for your dash and seating, the steering box doesn't care. You can cheat the cab over if that works for wheel wells, trans, bumpers and all kinds of other problems. You can cheat the motor over a little, driveshaft can be a little crooked, but the tranny shifter, exhaust, fan and etc. will have to be considered. How close is too close depends on what you are talking about specifically. The above cheater items are not recommended, you can get yourself in a catch 22 situation before you know it. Much, much less trouble keeping EVERYTHING symmetrical. Borgeson will answer your heavy duty questions, If you have power steering, there is no "heavy duty" stress on the steering Ujoints.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn