JC Whitney use to sell them for $179 according to a four year old catalog that I have. Have no idea if that is still the case. Looks like a lot of dents for $100, but that's my opinion. Mine didn't have a dent and didn't need one. I bought mine used, but still in the box about fifteen years ago. The guy had bought them to put on his lowered Chevy II project, but because they are made to fit the 250 and 292, they were much too long and almost touched the ground.
the surface that contacts with the header is not quite flush,
By that, I assume you are referring to the surfacing of the weld on the inside of the flange. A lot of headers are that way so that they don't cut through the weld.
I have two suggestions that will save you a lot of headaches and frustration.
250/292 heads came with two locating pins. One on each end. Inboard of each of those is a threaded stud with a fine thread nut. All the other manifold fasteners were bolts. The pins are threaded in and can be removed. Replace those and all the bolts with studs.
The header flanges are not very thick and will warp easily and leak.
The stock manifold gasket will not work.
Most people here will tell you to get a Felpro header gasket. I recommend the cheepest one piece header gasket you can find. I tried a $30 felpro and it lasted one week. What ever gasket you choose, do NOT overtighten it. I will leak for sure.
Holding the two header pieces, the gasket, and the intake against the engine and starting the bolts is a juggling act. The studs make the assembly very easy and helps with the gasket sealing.
