Hi,
All the screws on those American kits of that era were 4-40 or 5-40 if they were larger.
For allen drivers you'd need:
.050" for the grub screws.
1/16" & 3/32" for the 4-40 screws, it depends on the head of the screw if you need the small 1/16" or the larger 3/32"
This style of screw would use the 1/16"
This would be 3/32"
But both are 4-40 thread. So depends what you are putting together, what screw you use.
MiCk B. :-)