I would assume yes. Non-oem heads, hopefully aftermarket rockers, aftermarket cam and lifters, possible decked block, lifter pre-load, and head gasket thickness are just a few variables to change length then you need to get the rocker geometry correct.
Most certainly everything is all aftermarket except for the block. Block has been decked a little more than my liking but I am making do. This is my first time building a big block of this magnitude or a big block at all for that matter.
Best thing I can say is get an adjustable pushrod. You can start with the stock ones if your rockers take a ball end, it will give you an idea of what length range of adjustable push rod you need. You also need to find out if your lifters/rockers need 5/16" or 3/8" pushrods.