It's really your personal preference. If you're using the disc/drum master that was originally one of the original master cylinders used on that booster, then the pushrod length should be a no-brainer. The Mopar one may require a little pushrod modification. If you had SEFI, I would recommend the Hydratech part number because the ports on the Lincoln master would come out right into your SEFI upper intake. But that doesn't appear to be the case in your scenario.
I'd say go with the one you like and there are plenty of people here who can help guide you with any questions you might have along the way.
If you lived around here, I'd say I'd come over and work on your truck if you'd let me take your Johnny Popper for a spin

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Todd Z.