I'm thinking the OP understands the requirement of changing all the resistors and caps in the "stage" where the 2n5088 is, in order to replace it with a tube in the same "stage", as part of a larger, more complex circuit. An analogue to this same procedure would be plugging either a tube based stompbox or a transistor based stompbox into an amplifier. They're electrically connected the same way replacing a transistor stage in a multi-stage circuit is electrically connected. I can't think of any reason why it wouldn't work to replace a transistor with a tube in this sense (provided you had the necessary voltage difference required for anode, the volt/amp required for the heater, etc), but midwayfair is right the OP is way too open ended with the question.