People that really know what they're talking about will chime in soon, but you'll want to reduce weight and open it up to let it breathe.
We ported and polished the cylinder head and did a valve job. If you don't have the tools and knowledge to do this, your best bet would be to send it to Jon Logan at
http://www.midwest124.com He knows where to take the meat off and how to port match the head to the manifolds at a reasonable price.
The block was machined. I went with .040 over pistons. The one thing you'll run into with the 1608 is trying to find pistons. I had to have mine custom made which can cost you up to $200 a piston.
You can get the flywheel lightened to reduce weight and also get some lighter pullies. Miller's Mule
http://www.millersmule.com/ does some fine work for our 124 Spiders at reasonable prices. When you get your lighter components, it's important to have everything balanced to the block by the machine shop. I bet I lugged my block and various parts to the machine shop 4 times before everything was done.
Cams would help performance wise especially if you open up the flow (intake/head/header). I'm running 42/82s on my 1608 and I have smooth idle and transition through the rpm range with my 40 IDFs. Some people believe these are two radical for a street engine but I believe since my engine is balanced it makes a big difference.
IDFs are fun little carbs, especially if you have a Jeff Scheferman in your pocket to help keep them tuned, but you can also go with a single plane manifold from an early 1800 and put a nice sized single carb on it for a great performance gain.
i want it to look awesome for 
