Small Block Chevy Question

[rmb_cobra]

I recently had a leaky head gasket that was beyond my skill set to replace. It was running great, with a little coolant leakage on the headers making the motor smoke like a steam cleaner. While the shop had it torn apart, I had them put in a new cam/lifters to give it a little more power. A moderate Lunati cam kit. The motor is a '69 350 SBC, box stock rated at 350HP. The heads have been ported and polished and am running a 650 Holley. The bad news is that it now runs like crap. Idles too fast (around 1500 once warm), the plugs indicate it is running too rich, and when I accelerate hard it pings like crazy and misses a bit, and the power is 1/2 what it used to be. When the mechanic tried to time it, he said it shorted out/nuked two different timing lights so he guessed at the timing which allowed for a good idle, took my check and said "call me if you have problems."
Any suggestions? I need to take the car back this week. Where do I start?