Head Build

I am piecing together my first 850 MKII Commando and I am about to start on the head. It's a good bare RH4 head so I was wondering if there was any advice you guys have regarding how to assemble it. Any modifications I should make to aid reliability and longevity? Not really bothered about making the bike go any faster I just want a leak free reliable head. Thanks in advance.

The valve guides are prone to coming loose on one of these heads,also prone to the head cracking if you fit an oversized one ,they are best left to a Norton specialist.
Also the cylinder head studs are easily stripped as are the exhaust threads.
Another common mistake is to fit the rocker spindles upside down cheers

Also although not essential you can shim the rocker gear so that it's central to the valves,

I wouldn't hesitate to call Jim Comstock and ask about his head services. Bronze inserts for exhaust, inserts for stud bores, valve guides, seats and valves. And I would listen to anything else he had to offer whether I decided to do it or not.

You can buy a bolt kit (not cheap) for the head now, bolts waisted (undercut) to permit stretching as the head expands.
You do have to modify the head slightly.
https://coloradonortonworks.net/cnw-head-mounting-kit.html
CNW part # 0800-30