Will the newer 'normal contour' Ruger synthetic stock fit as a direct replacement for the earlier 'boat paddle'? I came across a boat paddle MK.II in .338 that I'd like to have, but that stock reminds me of a one-eyed, evil spirited, hard kicking horse I used to have.

The new stock will drop right in. It will sound like a drum when you bump it to something with it. I myself much prefer the "Boat Paddle", as it is much quieter and a stronger stock.............

A quick fix for those empty sounding synthetic stocks is to get some of that expanding foam in a can, take off the recoil pad and fill it and fill the voids in the barrel channel as well. Really gave a different feel to my 6.5x55 that came with a ramline stock.
Yes I agree your .338 will drop right in.

I bought almost all of my Rugers with the boat paddle stock and stainless actions, so I could replace the stock with a laminate one...

But I have two Hogue Rubber stocks, that are pretty nifty when you are out in really tough conditions and crappy weather...

i had one of those rugers but i fixed it with a nice piece of walnut