we replacing a headgasket for a b18b1 engine, does anyone know if a headgasket made for a b16 will fit? buddy works at honda and gets them 20 bucks off

also im installing my header on saturday and i guess they dont come w/any gaskets. is it okay to reuse my original header-head gasket w/20k miles, and also is the header-cat gasket the same as the stock one (size wise)...so will it fit around the collector, im assuming i definately need to replace that one...