The 228 is a good solid engine, I have never heard of any particular problems associated with them. Parts are still available to rebuild them, plan on spending a little more on GMC engine parts than those of a Chevy 216 or 235.
As for a salvage yard price, the yards around here all get about 300 for a motor. I am not sure what is a fair price in your area. Be sure that no matter what the price, that the salvage yard owner stands behind the motor. The first thing you will need to do is get the motor magnafluxed and checked for cracks. If you have a cracked block or more commonly a cracked head, he should replace it or refund your cash..
