I recently ordered a 'classic' silencer from Hitchcocks (part 91080) that is a straight swap for the stove pipe fitted as standard on my Electra EFI. It has a removable baffle and is fully compatible with the standard ECU. Along with that I ordered a 30cm long 'universal' heat shield (part 91043), which came with a couple of stainless steel Jubilee clips.
This covers the join between header pipe and silencer, also the tab on the downpipe that held the front of the original heat shield. I had to flatten that tab though, or the heat shield stuck at the front. I also had to fiddle about with the placement of the shield so it didn't foul the kickstart, which I use for freeing off the clutch when the engine is cold. It seems to give the starter mechanism an easier time.
The result looks great. The finishing touch was the fishtail (part 91095). On the old silencer this was just cosmetic. On the new one it takes the hard crackle off the exhaust note, but doesn't stifle it. It seems that Velocette developed the fishtail end piece in the 30's in response to complaints about the noise their sports bikes made, especially in towns. So even in the 30's, bikes were deemed by some to be antisocial.