go to autonzone if you have it
and goto the aftermarket performance section(thats what i call it) they have all sorts of stuff for 302 and 350's and a coupld of ricer parts(fart cannons and intakes) get two packs of these bolts they are gold and really good grade. there like 6 or 8.00 a pack. also they have mr.gasket 302 header gaskets that i recommend over the felpro set for the same price as the felpro's like 12.50 or something. plus they are larger/thicker gasket to help with the larger prots and flange difference. i dont see gasket failure to be a problem with mine, and it looks like we have the same headers except my falnge is not flat and mine were not 3".
like mentioned before, spark plugs were not a problem i didn't even pull my off since they were never really in the way(be careful though). you need new bolts for sure, and i am pretty sure if you are on stock motor mounts the drivers side header is going to hit the frame, and may hit the steering shaft thing(where it connects like a drive shaft yolk) i forget what it called,lol......oh yeah i forgot you cant use the dipstick mount either cause the mount wont fit with the new header tube size.....and the things that you use to hoist a motor out(i cant remebr the name either) wont work either, the new tubes are to large, i was going to grind mine out but when motor removal comes there are other ways to do it.......
but overall its not too bad one day install a weekend tops..harder than what i expected being such a simple mod, but it also was my first time and i had to learn the hard away about the header bolts not fitting, and for some reason fitments is never fun for me..
.
