Savage Model 1903 Barrel Replacement

I have one with engraving, bird dogs on either side and checkered stock. Picked it up in a gun shop around 1967 (for sure before 1968 GCA) for $10. Owner of shop told me someone had stolen the magazine out of it while on display. Never have done anything to it.

Someone had also done a crude attempt at putting a 20 inch round barrel on it. The receiver appears to be threaded but the replacement barrel was simply pinned in with a screw (apparently added) through the receiver. Didn't work very well.

Would like to put another barrel on it. Does anyone know the thread size of the receiver or original barrel? Also recently picked up a Triple K replacement magazine for it.

Serial Number is 70.1xx

Edit: Found out over on another forum that the rifle was made Summer of 1908 per serial number and is a Gold Medal grade based on the engraving and checkered stock.

Also think the receiver is threaded 5/8 x 24 per thread pitch gauge. Thinking about taking it by a gunsmith to see if another barrel can be put on it. Probably cost more than rifle is worth but would like to get it in shooting shape and pass it along to my son. I realize these rifles were not designed to shoot Hi Speed ammo.