The "G" serial prefix merely indicates a generic Model 70 and can apply to either push or controlled round feed; 1968 or later rifles. The earliest POST 1964 CRF Winchesters were from the 1991-92 era and subsequent.
I can't comment about receiver swapping other than to speculate 'a problem' and result likely jury-rigged. The barrels would not interchange on the actions without significant work, if that's what you were intending. If swapping barreled actions, the barrel profiles would likely be different and either significant channel work or glass bedding to accommodate gaps. There are also matters as bolt handle cuts as well as bottom metal configurations. The short answer, 'possible but impractical'. Aesthetics and resulting market value likely suffering!
By the time you acquire a CRF rifle, presumably cannibalize it; end up with a mismatched push feed & CRF stock; likely better investment just to buy a nice CRF rifle and be happy with two ORIGINALS!
My early nineties off the shelf 70 Super Grade, 338 Win Mag, with a handsomely figured stock, paralleling the 'custom level' pre-'64 SG.
My take
