On a stock K member, you may need to grind/cut around the passenger side primary.. it may hit.
Also, the steering column will need to be slid over, which is a simple matter of loosing the bolts, sliding it over, and re tighten. For 310 shipped, you cannot beat these headers IMO.
As far as being "too big" for your application, I ran the same time I did with pacesetters.. so not sure how I am losing HP/Tq there...
I run my wires under the headers with no issue and spark plug access is much better that the pacesetters. The header flanges are 1/2 inch and the end holes are slotted so it makes install a breeze. The collectors are actually welded by someone that isn't blind and there is no coating to fall off after a year of driving. If you take the time to work over your engine harness, you will not need 02 extensions anymore either.
The one downside I have found is the Y pipe supplied is garbage, I think cause they use the same one for LT1/LS1 setups, but small price to pay. I got my headers from AP1AP2, and am very pleased with them.