If you had $2K to play with...
What sort of valves, head-work, etc, etc, etc...
Good source for valves
here.
I forgot to mention cam, pistons and rings as well, as well as some ARP hardware for safety (don't want to throw a rod now do ya?).
As far as head work, it depends on your piston and cam choice. There is a good amount of homework involved, like figuring out compression ratios and what not.
From there, the machinist will know what kind of work to do to your head. I know a few members (I think Frank is one of them) on slantsix.org do headwork. I'm pretty sure he is pretty busy lately, but I'm sure they will be more than happy to recommend a place for you to get the work done.
The head is where all the power is going to come from, and if not done right, your wasting your hard earned cash just bolting up parts. Headwork alone will run you near $1000 if not more.
I know Doug Dutra sold a nice, fixed up head on the SL6 site for like $900 or so not too long ago. I'd suggest (like some of the members have already suggested) to go to the slantsix.org site and do some reading.
Also, if you ask on that site, you will get more answers, faster.
I am in no way an expert, but a performance SL6 isn't just a "bolt on deal". There is no aftermarket aluminum heads and stroker setups.
It all has to be done the "old school way", lots of research to combine the right parts, math, machining and of course the most important ingredient.....
american greenback.
Hope this helps you out a bit. SL6 aren't for everyone, but they sure are fun and they last a really long time. Not to say V8's aren't fun either, they are just all fun in different ways. That's why I have a SL6 car and a BB car.
It's all Mopar at the end of the day anyway! Good luck bud! :D