Re: 4V heads
Depends on how good you want them to look as well as and more importantly, how reliable you want them to be. That is, it would be a smart move to get them acid dipped and then pressure tested for cracks.
You may not need nor want to do this, but the time is definitely now as compared to going to all of the effort of cleaning them yourself, putting them on and to have them spring a leak or look shithouse (paint wont stick) if you didn't prep them well enough.
Simply put, all depends on what you want out of the engine/car. Lastly, are the 4 dot 4V's or the older straight 4V's?