Nothing wrong with reusing Roller Lifters & Cams, they're not like a Flat Tappet Cam & Lifter parts which shouldn't be swapped into other Engines. As long as they're in good shape, Rollers roll smoothly etc..
They're scattered all over Ebay/Craig's List etc.. cheap.
Your choice, if you've got the $$ & feel better with new parts go for it.
Howards brand are excellent parts.