i'm swapping valve springs on my 383 with mild cam(480-490 lift). i have an installed ht. of 1.87 - the springs i'm looking at have inst. ht. of 1.82. question is... will .050 in. make a diff. or should i use shims or taller springs?

Compcams has single springs with dampner inside that works good for that lift. They would be 911-16. They have a installed height of 1.900. You will need a shims. I don't think using shorter springs for a .480 lift would be a good idea no matter how many shims you use to get to 1.870! I hope this helps you! Just my opinion!