It's hard to say if the engine noise is normal or not.
All of the Royal Enfield engines make more noise than modern water cooled motorcycle engines do.
All of the Iron barrel engines have adjustable valves that occasionally need to be adjusted and even when they are set up right, they still make a little noise.
The cam drive gears are "straight cut spur gears" and with a little wear on the teeth the slop between them can cause some noise too.
The Iron barrels also run a bit more piston/bore clearance that will make some noise, especially if the engine is not fully warmed up.
Not to be too romantic about it but, these are all the sounds of the past that were just accepted as normal "back in the day".
Of course, if the engine is making loud pounding or clattering sounds, it may be something that needs looking into.
These old Iron barrel engines used a aluminum connecting rod with a free spinning "floating" bearing on the crankshaft throw.
If they are pushed to hard (read "fast") the iron cylinder can't get rid of the extra heat so piston galling could result in wear and damage.
Although it is a 500cc engine with enough power to go faster, these Iron barrel motorcycles are happiest with a top speed of maybe 55 mph.
If it's hot out (like it is here right now), a top speed of 50 mph would keep them even happier.
Ride it easy and you shouldn't have any problem.
Oh. Use the forum's search engine and look for "adjusting brakes" in the iron barrel section. There are a lot of good posts that discuss it.