These sizes aren't exactly stock, been awhile since I sold SS but I know these sizes will get you close for your ratrod style build. You'll go broke buying single bolts. If you can't buy by the pound, get a box of 100 where it makes sense. Get coarse thread stuff to save considerable money. Some carriage style bolts are generally used, but if the square holes are smoked you can use hex bolts for better result. If you don't use nutplates, the front clip has about 500 pieces of hardware.

Box of 100
Capscrew (hexhead bolt) 5/16- 3/4L
5/16 Flatwasher
5/16 lock washer
5/16 nut
1/4 flatwasher

You'll also need the following in smaller approximate QTY.
1/4 nut-12
1/4 lockwasher-12
1/4 bolt by 5/8 or 3/4L hex bolts-12
5/16 fender washer-12
5/16-1" Long bolts for a few places a 3/4 is tough to start=12.

Radiator SPT to frame will depend on how big the hole is after you clean up the rust Some 3/8 bolts usually suffice.

That will keep you busy. You'll figure out what else you need when you get it close. You'll have stuff left over for other parts of the truck.