All the OEM 426 hemi motors that came with solid lifter had .032 lash, correct
I always tighten the lash up some( 10 to 25%)on all the loose lash cams I have used in my motors and recommend it for customer motors also
What rocker arms and camshaft are you using? What is the recommend lash ?
If your using all new valve train parts they will wear some after start up and breaking in, that will add clearances on the lash, once all the parts are broken and seated the lash should stay where you set it
If it doesn't there is a reason for that, abnormal wear or parts failing
Good luck on your deal