The springs should (and in my opinion, must) be fitted. They are so easy to fit that this whole thread almost beggars belief! 10 minute job, at most. Why on earth would anyone NOT refit them having done any work on the heads? If you were to refit the rocker shaft block upside down by mistake, then realise a minute later when fitting the spring, it's 2 nuts and 2 minutes to slacken off and put right. I know coz I've done it.
And while I'm on a rant, no silicone sealant on the pushrod tube seals, please. Just get the faces really clean with no screwdriver gouges, nicks or burrs, plenty of grease on faces and seals, then gently slide and twist into place. If it wont go, don't drift in as this is when seals can be nipped and will leak from then on. Clean it again, grease it again, and try again - it will go in when it's right, and won't leak. Then put the bloody spring back!
The Campershack - (website paused) WBX Rebuilds & Upgrades from the beautiful Isle of Arran