I agree with the others, I would not bubba/"modernize" a Garand. You could sell it to someone who just wants a wall hanger and buy a better functioning Garand (a lot less money than the work you're considering) - or get an M1A if you really want a box magazine. Or get both!
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek