Without knowing for sure I think Jurgen Hecker makes them. Or was it Richard Schonfield? I think Moen at IPE can guide you right. I got some pics of new ones made in "Böhler EN36A steel, hardened and ground" But dammit, I forgot to note who made them.

I found notes on Jacob Junkers site "Indian vintage cycle bay" where you sometimes can find those lifter guides for sale (mostly used but sometimes he's got NOS parts) and the excellent picture display and descriptions can be used as reference for many different parts. Scout has 2 different heights of guides "Early Scout low, 0.652 in. base to top, and Early Scout tall, 0.790 in base to top. Both are the same overall length 1.543 in. Both are knurled at the base.

The 101 engine has the lower guides. But make a thorough research on your engine. You have to make sure you get the right height and that the stem is ground to suit the hole in the crankcase. And the lifters has to fit the holes in the guides. Used lifter guide holes are commonly broached to a larger size and lifters are ground to suit that. You have to research and make sure you get parts that fit.