I would take your grandad's gun to the range with a box of modern ammunition and to the gunsmith. If it keeps within 1.5 MOA and is mechanically sound, I would save your money for optics and boots.
My brother has an 06 with an old push forward Enfield action probably rebarrelled that he was given by our grandfather.
I never would.have given it time of day. He shot it and it was accurate. Had a gunsmith install a timney and a recoil pad.
Now it's a good rifle and who would have guessed. Now he.says it doesn't shoot well when he tightens the action bolt down. I think he just wants to buy a new toy