Carby/s, exhaust, cam.. In that order.
Carby is a difficult one to price. If you're lucky some people will give them to you or sell for under $100, but
if you're looking for a rebuilt or one off eBay you'll probably pay upwards of $150-$200 for a 32/36 weber or similar.
then the adapter plate you're looking at $25-$50. All up $100-350
Exhaust looking at quite a bit if you aren't going to do any yourself. Extractors (new) cost about $250-$300
or $100+ second hand. Then you'll need to spend atleast $300 on a 2" exhaust.. All up $450-650
I've never had a cam reground or changed in my car but I've read it's about $80-$150 for a regrind from Tighe Cams,
Crowe Cams etc. Tighe 104 is supposed to be a good grind (as said in "How to build a tough K motor"). That is if you
remove/install the cam yourself. I have no idea of the cost of the mechanic work but probably not too cheap!
Good luck