Talk to Jerry at deadbolt for the port work. I dont know if he does manifolds. I could do it for you probably a bit cheaper if I had a compressor (I sold it before my alst move, so I cant), but I bet Jerry could do that as well. IAP Performance (eastcoast scooby) sells manifolds for like $100 so you dont have any downtime. The key on the manifolds is port matching and smoothing.
For the GM solenoid, I dont have the link handy, but there is a HUGE thread, and if you have a buddy at the dealership, its a $13 part.