There's no oil supply gallery to the lifters, so tubular pushrods are a moot point. The first 235 with hydraulic lifters came out in 1950, in passenger cars with a Powerglide transmission. Those engines had solid pushrods, with a slot ground in the bottom pivot ball to allow air to purge itself out of the lifter. Trucks with 216 or 235 engines always had solid lifters, and solid pushrods, so your tubular ones can't be original. Does your rocker arm shaft have an oil line plumbed to the connector at the center of the cylinder head?
Jerry

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