Dang, if you are starting with a legit Shimmel 3L block I would still to keeping it as clean as possible. Not sure if you'd benefit from a 3.6L head or not, or if its even possible to swap
That being said, there arent too many options for 24v valve but you cant go wrong with Eurospec or CAT cams. Both have the reputation and resources to make quality products.
MAke sure you have a really good tune for it as most 24v canned tunes are meant for 2.8L and If you can run e85, I would do that all day long for more power.
Some water/meth later down the road and this should get you a nice 250-300 NA whp