I would be very surprised if a coil or MSD box would make any noticeable difference on anything but the most modified high performance versions of these engines.

For example: I am running the Nology coil and hot wire on my race bike which is N/A, RHC 187 cam'd, now sitting at 13.5:1 compression ratio, full balanced, RHC head etc etc. The only thing I noticed when I installed it was maybe easier starting and smoother idle....maybe. I didn't get much if anything in the way of a noticeable seat of pants power increases on this setup which should highlight these types of gains.

So, if you don't need race gas or aren't running some nitrous or something I would say save my money for something you'll notice more.

 

An MSD ignition box will give you a little more jump off the line in a stock application. But you need the coil and wires to handle it as well. I've run it both ways and there is a noticeable difference.