I think a real mechanic is a good idea.
The manifold nuts at the head are copper, so they shouldn’t be rusty. The studs may be rusty but soaking them with penetrating oil will help. I always get new studs and nuts, or nuts at least and chase the stud threads with a die if I’m reusing them. New gasket goes without saying, but, I just said it.
Get what’s left off the car and on the bench so you can work on it. You’ll have to fit up everything on the car, unless you bought OEM parts. Leave all bolts loose until it’s all in and on the hangers. Then start tightening bolts. |