I put the spacers in when I installed a 600 cam. I pulled the jugs to cut the bases to get the compression to 12.2 so the heads were off. That effectily made my pushrods .060 longer and I did not use lash caps. I know you are saying they are adjustable push rods so what is the worry. When I did my first prototype I made it .200 thick and with travel limiters in lifters the there was not a lot of thread engagement on the adjustable push rods. The .100 worked better for the geometry anyway.