440 source/push rod clearance issue

Went thru the same issue last fall,like the other guys said ,you can call manton or smith bros.and they can make you some smaller dia. pushrods,You did not state how big your cam is,but distance travel and spring pressure figure into this as will lenght,I had to grind along side port runner and in the push rod travel area,end up pulling heads and completely dissassembly to remove any chance of shavings getting into motor.I would definitely mock you motor up as you are going to run it ,rocker arms included and slowly turn you engine over.take a maker and mark where pushrods are hitting(refence point)just in case the smaller dia. pushrods still hit, kind of a cya (cover your ---) don