This is one of the few applications where you are going to need to order your headers for that particular car. It is very tight and generic 350 headers are not going to fit. You will also probably need to have the collectors welded to your exhaust pipes to ensure you don't have exhaust leaks getting inside the car.
Most Chevy 350 4 bolt engines will bolt into a 1979 Corvette.
The 90 Corvette had a 350 c.i. engine
diagram of motor od 1981 corvette
Yes, the block will fit.
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Yes, the block will fit.
Yes. They will bolt on any small block, prior to 89. However, hedders are made for the car. Camaro, Chevelle, pick ups, ect. If you are just swapping motors fine, but, if you do not know what the hedders came off of, then they may not fit your car, and will hamper your steering, and have other clearance issues. Don't try it. A new set is only $100, or so.
350 CU.In.
.019
5.7L 350
L-98 350 cu. in.
About $1700.