Before going down that route, you could try checking a few things.
Tyre pressure, tyre tread, tyre width, strut pan bearings, tracking.
Did you use ser 2 struts with new plastic fag bearings, if the bearings are not good the steering will be heavy, ser 3 have another bearing in the top mount which helps.
What width tyres do you have? wider than 195's will make it heavy. If the tyre depth on your tread is low it makes the steering heavy due to less block tread movement, I notice a difference when buying new ones.
Try your original wheels first to see if it makes any difference.
For road use I have my tyres at 35 front 32 rear, drop it to 28 25 for a bit more grip.
It maybe that the mrs is used to powersteering, it takes a while to get used to not having it.
Does your crank pulley have a spare groove, if not you will need to swap it over, not an easy job, they're FT!!
I have a ser 3 and swapped the power steering for a non PS rack
I get the same thing over bumps, need a harness to keep you in the seat