I am building a 95 lt1 383 someone told me that the block does not have to be clearanced for the stroke. Does anyone know if this is true? Also need a good header bolt any suggestions? What thread size

 

You will know during preassembly and it likely will have to be clearanced some. ARP bolts are great

 

If your using stock rods the bolts on 1,2,5 and 6 on the inside will need to be clipped to clear the cam or get a small base cam. If you are using after market rods they will clear the cam. You will need at least .050 clearance between the block and the rod. If you can get a bushed rod or hone out a stock rod, put the piston on the rod with out rings and check for clearance before you start installeing the cam bearings and such. You might have a lot of cast iron floating around if you do some grinding for clearance.