The problem is Your NOT restoring the Rifle . Because it Never was Completed . Now if it had already had the holes drilled for the Pins then that would be a Restoration . It is IMPOSSIBLE to Restore something that never was .
To many of these UnFinished LSR`s have had collectors and Unscrupulous types do exactly what You are contemplating and in the end these Post War Completed Long Side Rails get Sold as Period Original Long Side Rails . I would bet that the people that own such an example have NO Idea that what they believe to be an Original is really not , sadly if You point this out to them they usually dismiss Your comment as being disingenuous .
Every so often a Real LSR that is missing its Base can be found for sale . I would suggest waiting and doing a Legitimate Restoration. Please do not turn another 3 hole BCD 4 into a Post War forgery !!!!! Best Regards