i am going to be installing lt4 springs...
i need to know if it is neccessary to use the valve spring micrometer for oem lt4 springs on stock lt1 heads and valve stems?

if you are certain please chime in...

thank you

 

Will you destroy your engine without one? Probably not. Will each spring have the correct install height without mic'ing them? Definitely not.
When I did mine, I only needed to shim two of the springs and they weren't very far off. Conversely, a good friend of mine needed shims on most of them (10 of 16 if memory serves) and some were off by a good bit.
I would very strongly recommend using the mic to ensure proper installed height for each spring. What's the worst that could happen from making sure everything is "right"?